Field Testing, and

Certification, Field Testing, and Calibration


An important aspect of any interlock program is the approval of devices for use and the subsequent testing of these devices to ensure that they comply with state-driven regulations and requirements. The development of processes and protocols to manage the certification, field testing, and calibration of devices is essential to maintain program integrity and to enable program administrators to effectively manage interlock devices that are approved for use in their jurisdiction. Ultimately, the implementation of these protocols is essential for jurisdictions to demonstrate the quality of the program, due diligence on the part of the jurisdiction, and to protect against potential liability.
The focus of this section is to provide program administrators with much needed information about the certification, field testing, and calibration of interlock devices. More specifically, this module is designed to identify:

  • baseline features associated with the certification, field testing and calibration of devices that programs should implement;  
  • additional steps that can be implemented as is feasible and practicable to further build on these components; and,  
  • examples and templates of preferred models, protocols, and approaches to enhance program integrity and to help ensure that devices adhere to program requirements and administrative rules.

Questions & Answers (Instructor Material)

  Who has the authority to certify interlock devices?
  What key elements should be included in any request for certification?
a) What are the requirements for a lab certification to be accepted?
b) What tests should accredited labs perform?
c) What pieces of information should be included in a lab certification?
d) Are there other steps beyond lab certification that jurisdictions can take?
  How frequently should jurisdictions require certification/re-certification?
  What modifications to devices should trigger re-certification?
  What types of internal quality control processes related to devices should vendors be asked about during the certification process?
a) What should be the focus of state field testing?
b) What is accuracy and precision of interlock devices over time and why is this important?
c) What is linearity and why is this important?
d) What is lab mode or metrological mode?
a) What is field testing and why is it important?
b) What does a field testing protocol generally entail?
c) How frequently should devices be field tested?
d) How should devices be selected for field testing?
e) How can field testing be funded?
a.) What are important requirements for service centers with regard to the handling of devices?
b.) How can jurisdictions manage service center non-compliance?
a) What is calibration?
b) What is the difference between wet bath and dry gas calibration? What are the issues associated with each method?
  What is the difference between alcohol interlock and evidential breath testing devices?
  What types of legal challenges to interlock devices should be expected?
a) What types of documentation do program administrators need to demonstrate that devices are operating properly?
b) How do program administrators ensure data security?
  How can jurisdictions ensure their procedures/protocols protect them against legal challenges?


Instructor questions & answers - Word file
Instructor Slides - PowerPoint file
Student Handout - Word file




1) Who has the authority to certify interlock devices?

The authority to certify interlock devices can be outlined in legislation (often within the interlock statute itself) or administrative rule. Ideally, authority and responsibility to certify interlock devices should be designated to a single state agency. This helps to ensure uniformity and clarifies decision-making. The designated agency should play a lead role in the development of the process and determine the requirements of device certification for a jurisdiction. In some instances, this agency will also have the authority to test devices.

There are several options available when it comes to certification authority and oversight, such as each state’s Department of Transportation (DOT), Department of Motor Vehicles (DMV), the breath testing lab of the state law enforcement agency, the Department of Corrections (DOC), or the Department of Health and Human Services (DHHS). It is important to identify which agency is the best-equipped to assume responsibility for certifying devices. However, it is also necessary to take into consideration whether the chosen agency has the requisite expertise, resources, staff, or willingness to take on the responsibility.

Perhaps the agency best-positioned to manage the certification of devices is the agency that is designated to oversee the approval of evidential breath testing devices in the jurisdiction. Even if this agency is not directly involved in the administration or delivery of the interlock program, it will possess the unique expertise required to approve these devices. Moreover, these agencies already possess the lab and instruments necessary for testing at their disposal. Several jurisdictions, such as North Carolina and Oklahoma, utilize this strategy.

It is important that the designated agency clearly understands that interlocks are designed to incapacitate a vehicle and are not designed or intended to provide evidential breath tests to measure BAC for the purposes of criminal prosecution. The device readings are meant to be used in administrative hearings as opposed to use in trial or, in the case of court-based programs, for the purpose of ensuring compliance with a probation order. Hence the typical burden of proof that these devices must meet is “on a preponderance of the evidence” as opposed to “beyond the reasonable doubt”. In some cases, the agency responsible for device approval may be inclined to push for devices to meet the higher evidential standard however, it should be underscored that devices are not required to meet this higher standard as part of existing programs in the United States.

An additional consideration when designating the authority to a particular agency to certify devices is to provide for that authority to charge fees as needed for this process. It is critical to include this provision in the same law and/or administrative rule in which certification authority is designated.

Court awareness of authority. It is important for courts to be aware of the state agency that has the authority to certify interlocks. Particularly in court-based interlock programs, it is beneficial for judges to have an understanding of the quality of the technology that is available within their jurisdiction. As outlined in Question 2b in the Research section, judges are often reluctant to order devices due to misconceptions related to device effectiveness and the operation of the technology. If judges are made aware that interlocks are certified to meet uniform standards to ensure only high quality technology is approved for use, it may increase judicial buy-in and consequently, increase their willingness to order the device.

In addition to having the knowledge of which agency has the authority to test and certify devices, it is also important for courts to be made aware of the following:

  • The required state configuration profile for devices. A configuration profile is a report of the settings of the optional features on the alcohol interlock. If there is an administrative program in the jurisdiction, these settings are typically determined by the interlock program statute or administrative rule. It is important that the courts are aware of this profile so that they do not order features or conditions that are not feasible to implement or that are in direct conflict with the statute or administrative rule requirements. If these features and settings are outlined in statute or rule, courts should be informed about specific setting requirements to ensure uniformity, and that they should not alter them in their court orders.

In order to facilitate education, the Judicial Outreach Liaison (JOL) can assist in the initiation of these discussions. Courts can also be referred to the National Center for DWI Courts (NCDC) Guiding Principles for Ignition Interlocks (available online: http://www.dwicourts.org/resources/publications).

2) What key elements should be included in any request for certification?

It is important to formalize a relationship between the state and interlock vendors/manufacturers1 to ensure that protocols exist that prohibit vendors from doing business in a jurisdiction if the quality of devices or services is not acceptable. Each jurisdiction may manage their relationship with approved alcohol interlock devices and vendors using different strategies. For example, a jurisdiction may require certification of only the interlock device, while others may additionally require certification of the vendor/manufacturer.

Some jurisdictions utilize a request for certification (RFC) which includes a list of interlock standards, requirements, and settings that each device is required to meet in order to be considered for certification. In these instances, the agency responsible for certification will require proof from an independent laboratory or state testing authority that attests that the device met the requirements of the RFC. In addition, other requirements related to device delivery and calibration methods/procedures might also need to be met in order to obtain certification.

For jurisdictions that require certification of manufacturers/vendors in addition to the certification of devices, further information is generally requested by the state authority including:

  • business plan;
  • ownership information;
  • details about operations in other jurisdictions (including their current standing and disclosure of any disciplinary action);
  • pricing and payment fees for installation and servicing;
  • insurance capacity; and,
  • proof that they have legal permission from the manufacturer to distribute the interlock in that jurisdiction.

Some of the critical issues that should be addressed in a RFC include:

  • the establishment of criteria for devices;
  • standards for the lab that provides testing of the interlock device;
  • service center standards;
  • form of data reporting;
  • violations and other reportable device recordings; and,
  • the required format of reports.

All requirements should be clearly outlined so as to avoid confusion and interpretation on the part of vendors/manufacturers.

The following components should be considered, as is practicable, for inclusion in an RFC or when certifying interlock devices:

  • National Highway Traffic Safety Administration (NHTSA) 2013 model specifications or the most current version (available online: http://aiipa.org/Resources/Documents/2013-BAIID%20Model%20Specifications.pdf) should serve as the baseline standard for device testing. All devices, at a minimum, should be required to meet these model specifications for certification purposes;
  • attestation from the manufacturer that they will comply with the requirements for configuration and operation found in state administrative rules or law;
  • device specification requirements;
  • lab certification from an independent and accredited ISO-certified lab
  • an indication as to how recently the lab certification must have been conducted (i.e., within a specified period);
  • field testing of devices as determined by the oversight agency;
  • requirement of notification of modifications including a definition of what constitutes a device modification and to whom it should be reported;
  • business plans; and,
  • current list of contact staff and notice of new employees. The list should identify which staff member would be contacted about testifying in court proceedings or administrative hearings, to whom a subpoena should be sent, and a requirement of the manufacturer to comply with legal proceedings.

The certification process may be structured such that an interlock device and the vendor can be approved at any point in time, or only at specific times of year. For example, some jurisdictions require all vendors to apply for certification by a certain date, after which point they can no longer apply during that calendar year. In many jurisdictions, certification is valid for a fixed period of time (e.g., X number of years), after which, the vendor must renew their certification.

If possible, it is beneficial to review RFCs from other jurisdictions in order to ensure your state’s RFC is comprehensive and exhaustive. An example of a list of state vendor specifications can be found at: http://aiipa.org/Default.aspx?pageId=1320420

1 Vendor is defined as an entity designated by the manufacturer to conduct business on behalf of the manufacturer in a jurisdiction. Manufacturer is defined as a person or organization responsible for the design, construction, and/or production of the alcohol interlock device.

3.a) What are the requirements for a lab certification to be accepted?

In most jurisdictions, interlock manufacturers are required to submit an independent laboratory certification report that states that the device model submitted for testing meets any technical requirements of standards required to obtain approval for use within a jurisdiction.

The laboratory that submits the certification report must be accredited. More specifically, the lab conducting the tests should be accredited to ISO 17025 (for more information see: http://www.iso.org/iso/catalogue_detail.htm?csnumber=39883) and qualified to test interlock devices. Similarly, all devices should be tested the same way to ensure consistency and uniformity within a program. One additional important caveat is that lab testing results should be current; it is recommended that only lab test results from within the past five years should be accepted by the certification agency.

The frequency with which devices are required to be submitted for testing is often defined in administrative rule or statute. In a majority of jurisdictions with certification requirements, re-certification (and subsequently, device testing) is typically required on either an annual basis or biennial (every two years) or whenever significant modifications are made to the device that affect its breath testing function. It is important for the state authority in charge of the certification process to clearly describe what constitutes a modification that warrants device testing and to whom modifications should be reported.

3.b) What tests should accredited labs perform?

Labs can perform a variety of tests in order to determine whether interlock devices meet state requirements for certification. Labs should also ensure that devices meet the most current NHTSA model specifications (see: http://www.gpo.gov/fdsys/pkg/FR-2013-05-08/pdf/2013-10940.pdf).

The following is a comprehensive list of tests that can be performed in order to test the performance, reliability, and durability of interlock devices:

  • Breath Alcohol Concentration (BrAC) accuracy and precision.2 Devices should accurately measure breath alcohol concentrations of 0.000 g/dL, 0.008 g/dL, and 0.032 g/dL BrAC.
  • Sampling requirements. Devices should accept only air volume samples that are at least 1.5 liters (or 1.2 liters, if medical circumstances apply and this practice is approved in a jurisdiction).
  • Calibration stability. The ability of interlock devices to hold their accuracy and precision over a defined period of time.
  • Lockout evaluation. Devices must be capable of locking out if not serviced within seven days of the recommended service interval.
  • Service interval display. Devices must, after 30 days, correctly indicate a call for service within seven days. Over the seven-day period, devices must display that servicing is required before locking out after the seven-day countdown period.
  • Voltage/power testing. If devices are powered by the vehicle battery, they should have accuracy tests at 11 and 16 volts.
  • Temperature range. Devices must be capable of reading accurately after exposure to extreme temperatures (-40F/-40C to 185F/85C).
  • Vibration damage. Devices must be able to perform after sustaining vibration similar to that of a vehicle in motion (10 to 500Hz).
  • Radio frequency interference (RFI). Devices must be exposed to testing near radio frequency fields similar to cell phones.
  • Re-test. Devices must be able to indicate when a re-test breath sample is required and, if the breath sample is not submitted, recognize this as a failed breath sample and recall the unit for service.
  • Re-start of stalled motor. Devices can be tested to verify if a re-start is allowed when a vehicle motor stalls following the initial successful start of a vehicle without the provision of a breath sample (if the vehicle stalls for a period of less than three minutes).
  • High altitude. Devices should be tested at pressure levels (80 kPa and 110 kPa) indicative of high altitude areas to confirm accurate operation in areas considered to have high altitude. High altitude should be considered to be 12,000 feet above sea level.
  • Cigarette smoke. Devices must be able to read BrAC accurately despite the presence of cigarette smoke in the breath sample.
  • Acetone. Device should be tested for acetone interference.
  • Tampering reports. Devices must be able to record the date and time of power loss as a result of tampering.
  • Circumvention detection. Devices must be capable of detecting and recording circumventions. NHTSA model specifications suggest tests such as hot wiring, push-start, un-warmed air sample, warmed air sample, cooled air sample, and filtered sample.
  • Data integrity and format. Devices must be evaluated to ensure readouts from the data recorder are accurate and understandable.

2 Accuracy is defined as the degree to which an alcohol interlock device correctly measures the breath alcohol concentration (BrAC) of a breath sample. Precision is defined as the degree to which the same measure can be repeated. 

For information on the European Union CENELEC standards for the testing of alcohol interlocks (specific to offender programs), please refer to: http://www.cenelec.eu/dyn/www/f?p=104:110:3768611831212088::::FSP_PROJECT,FSP_LANG_ID:23306,25

3.c) What pieces of information should be included in a lab certification?

The report submitted by an independent lab to the state agency in charge of interlock device certification should include the following pieces of information:

  • confirmation that the lab that completed the certification is accredited, including a certificate or proof of the accreditation;
  • confirmation that the device for which certification is being sought, is the device for which test results are being submitted;
  • report of tests completed on the device that was submitted for testing;
  • corresponding test results; and,
  • notarized statement from the lab stating that the device meets or exceeds the most current NHTSA model specifications.

3.d) What pieces of information should be included in a lab certification?

As is practicable and feasible, it is important that jurisdictions conduct either their own in-house lab testing or field testing of devices before officially certifying or approving them for use in the program. Jurisdictions may opt to conduct their own in-house lab testing to ensure that the device functions are working properly and that the device adheres to NHTSA model specifications. However, jurisdictions may choose to only field test the device.

The purpose of field testing is to confirm that the various features of the device are properly programmed in accordance with administrative rule requirements and that it properly responds in various situations as is prescribed. Some jurisdictions conduct field testing of devices prior to certification as well as at several points throughout the certification period. This allows jurisdictions to measure if devices meet the standards and settings required by that jurisdiction in addition to NHTSA model specifications. Field testing devices at random times throughout the certification period enables jurisdictions to monitor the performance of devices in the field on an ongoing basis as opposed to only testing select devices submitted by the vendor for the approval process. It is suggested that the procedures for field testing devices be described in administrative rule.

4. How frequently should jurisdictions require certification/re-certification?

Device certification. Jurisdictions vary in their requirements as to when and how often devices should be certified or re-certified. Preferably, devices should be tested and certified at the initial point of application to do business in the state and then again if there are modifications made to approved devices. Some jurisdictions require re-certification regularly although this can be onerous and a deterrent for vendors to do business in a state as the testing process can be costly (i.e., submitting a device to test on an annual basis is cost prohibitive). The agency responsible for certification should require the vendor to submit the following information for each device model they wish to be approved for use: date of the most recent lab testing/certification and certificate of product liability insurance naming the state or program as an insured.   

If devices fail the certification process, there should be a reasonable opportunity for vendors to address any identified issues and re-submit for additional testing. If certain devices or manufacturers are prone to failure, it may be important, from a program integrity standpoint, to require certification on a more frequent basis.

Certain jurisdictions require re-certification if device modifications are reported to the state by the manufacturer or vendor. Administrative rule should clearly outline what changes warrant re-certification and what is required of the manufacturer (please refer to Question 5 for additional information on device modification).

The development of a re-certification strategy is important. Critical questions include:

  • How frequently will devices require re-certification and under what circumstances might a device need to be re-certified earlier than scheduled?
  • How will modifications of devices be handled and reported?
  • How will new versions of devices be tracked and monitored?
  • Will the re-certification of devices include both lab and field testing or just the latter?
  • What features of the device will be tested?
  • What constitutes a failure or pass in testing for re-certification purposes?
  • If a device fails the lab or field testing process, what will be the procedure for alerting the vendor and what is the timeframe to allow for re-submission for testing?
  • What paperwork and level of detail will be required for devices to be re-certified?
  • How many devices will be submitted as part of the lab or field testing process?
    • Agencies may wish to utilize the same number of devices as is required for the approval process.

Vendor certification. As with device certification, in most jurisdictions, certification or re-certification can occur at any point in time. However, in other jurisdictions (e.g., Minnesota) there is a specific period of time during which new vendors can apply for certification or those previously approved can apply for re-certification. Ideally, vendors should be certified annually. If this is not possible, vendors should not go longer than three years without being re-certified. This allows the jurisdiction to request updated vendor contacts, copies of contracts with device users, and recent business plans. The re-certification process also provides an opportunity to provide vendors with feedback in relation to their device performance and service delivery within the jurisdiction. It is important to outline the procedures and timeframes for certification/re-certification in administrative rule or statute.

5. What modifications to devices should trigger re-certification?

A device modification is defined as a modification, upgrade, or alteration to any of the hardware, or firmware of a device. If any of these alterations affect the form or function of the device, the jurisdiction needs to be informed and there may be a need for re-certification.   

  • Firmware. The permanent software programmed into read-only memory - i.e. the “control program” for the device.
  • Hardware. The physical pieces of the device.
  • Form. The shape, size dimensions, mass, weight, and other visual parameters that uniquely distinguish a part of the device.

When considering what changes warrant device re-certification, the state needs to consider whether there has been a change to device functionality or to the breath sampling/breath analysis portion of the device. For example, changes to the alcohol sampler and changes to the alcohol analyzer are most important and warrant re-certification. Similarly, if the type of sensor has changed, re-certification is necessary.

Some types of modifications may only require parts of the device to be re-certified. Ideally, labs or agencies will test both the specific changes to the device as well as conduct random testing to determine whether the modification has affected the overall operation of the device. Changes to device firmware can potentially change the way the device functions; as such, the state agency should be notified of firmware changes and then make a determination as to whether re-certification is necessary.

It is important that jurisdictions recognize that alcohol interlock manufacturers are routinely modifying and updating various aspects of their devices. Consequently, it is necessary for program administrators to develop a plan to ensure there is an appropriate level of oversight in relation to devices approved for use within their jurisdiction.

Furthermore, program authorities should be aware that modifications are made to interlock devices on a regular basis depending on the needs of other jurisdictions. Manufacturers and vendors are presented with the challenge of having their device operate in different ways for each jurisdiction where they approved for use in accordance with statute, administrative rules, and/or technical standards. Most often, differences can be found in the device firmware to accommodate particular requirements of one jurisdiction. However, the firmware changes could be made to all models of a particular device which has the potential to create a conflict with required operations in another jurisdiction. Changes to the hardware, firmware and design can create a much different operating device than the one that was originally submitted for testing and certification.

States should consider including language in either legislation or administrative rule which requires manufacturers to notify the state in advance of any device modifications being implemented in the state. The language would not need to specify changes that would trigger a field test or recertification, but could generally state that after notification, the state would then determine if, based on the specific change, recertification was necessary. At a minimum, this can ensure that program authorities are aware of and are familiar with different versions of devices that are in use in their jurisdiction. The provision of clear guidelines by jurisdictions to vendors as to what modifications warrant notification and submission for further re- testing and/or re-certification is imperative. Jurisdictions are encouraged to consider how modified devices will be managed to ensure that any modifications are consistent with the most recent NHTSA model specifications and any state technical standards and that the quality of devices in use meets all program requirements. (Please see: http://www.oar.state.ok.us/viewhtml/40_50-1-2.4.htm for sample language).

6. What types of internal quality control processes related to service centers and devices should vendors be asked about during the certification process?

There are several standards involved in the calibration and installation of interlock devices which vendors and service centers need to adhere to within a jurisdiction. If a defined certification process for devices and vendors is not in place (i.e., a jurisdiction opts to certify one and not the other), program authorities should explore existing vendor quality assurance processes in detail. This is also good practice for jurisdictions that do have rigorous certification protocols in place.  

The following are examples of the types of questions that can be asked of vendors. Program authorities should inquire about vendor practices in order to increase understanding of how they maintain quality service delivery standards. This can have important implications for the quality of service delivery across a jurisdiction. 

Quality Assurance Plan

  • What is contained within the vendor quality assurance plan?
  • Do vendors follow state and federal regulations regarding business practices?
  • Is the vendor certified to do business in the state?
  • Has the vendor designated a contact person that the program authority can contact directly should an issue arise?
  • Does the vendor offer a toll-free customer service number?
  • Does the vendor provide 24/7 service response for problems?
  • What is contained within the service or lease agreement that vendors use with clients?
  • Does the vendor provide statewide service delivery?

Hiring/training of technicians

  • What background and work experience are required of interlock technicians that are hired by the vendor (e.g., education, employment/training)?
  • What qualifications must technicians possess?
  • Are all technicians subject to criminal background checks?
  • What is the training process for technicians upon hiring?
  • Can the delivery of training to interlock technicians and the performance of background checks be confirmed?
  • How frequently do technicians receive additional training? Is it delivered on an ongoing basis?
  • Is a technician, licensed by the jurisdiction or the vendor, always present at the service center during hours of business?
  • Does the manufacturer provide a designated help desk that technicians can contact for technical support as needed?

Calibration process

  • Who calibrates interlock devices and how are they trained?
  • Are the devices calibrated and data downloaded at the service center or is the device mailed3 to the manufacturer to perform these functions?
  • What method of device calibration is utilized (i.e., wet bath simulator or dry gas)?
  • What is the frequency of device calibration?
  • Are device readings provided to the ignition interlock user at the time of calibration?
  • Is a simulator log maintained?
  • How is calibration equipment stored (e.g., proper temperature)?
  • Is calibration equipment properly cleaned and maintained?
  • How does the vendor or manufacturer ensure proper functioning and maintenance of the equipment in the field?
  • Is proof of calibration available?
  • Where is calibration information stored and who has access to this data?

Installation process and servicing

  • How will each installation be reported to the program authority?
  • Is confidential client information kept in a properly secured area?
  • Are clients unable to observe the installation of devices?
  • Do technicians deliver the required training to clients that uses protocols meets criteria established by the jurisdiction?
  • Do technicians provide clients with appropriate paperwork and documentation?
  • Do technicians perform the required calibration and maintenance checks on all vehicles that are brought in for servicing? 
  • Does the vendor provide regular and emergency maintenance services?4
  • Does the vendor ensure that all service centers possess all of the diagnostic and other equipment, tools, and replacement parts needed to assure device functionality?
  • Do all service centers have approved interlock units on-site?
  • Does the vendor have a plan for the repair or replacement of devices?
  • What safeguards are used when installing devices to prevent or make evident tampering and circumvention?
  • How are monitoring reports submitted to the state authority and what do they entail?
  • How often are reports submitted?

3 There are two types of calibration and data download methods commonly used in jurisdictions. In the first instance, calibration and data downloads are done on-site at the service center location and data is electronically transmitted to the manufacturer. Less commonly, vendors are allowed to use a mail-in system. In this instance, the user is responsible to replace the existing handset with a new one which is mailed to them and return the used handset to the manufacturer.  The manufacturer then calibrates and downloads the device in one central location. Jurisdictions need to clearly articulate in administrative rules or statute whether they will permit the use of mail-in devices in their interlock program.

4 Programs that allow for a mail-in process of the devices should be aware that there is risk of increased tampering and circumvention by the offender due to the lack of physical inspection of the vehicle. If allowing for a mail-in process, programs should consider mandating a physical inspection by a service center as a part of the scheduled mail-in of the device.

7.a) What should be the focus of lab testing by jurisdictions?

Jurisdictional lab testing should focus on the configuration profile and the device requirements as written in administrative rule or statute as opposed to duplicating the testing conducted by independent labs. Whereas the independent lab testing initiated by the manufacturer is important to verify that the device meets the most current NHTSA model specifications, lab testing by a jurisdiction can ensure that the device adheres to the programmatic specifications set forth by administrative rule or statute in terms of the proper functioning of the device.

Of importance, jurisdictions should provide a clear and concise summary of the required settings for devices to vendors in order to avoid vendors incorrectly interpreting what is required by the state. If jurisdictional device profiles are documented in clear language, there will be greater consistency between the configuration profile of each device and the jurisdictional requirements.

7.b) What is accuracy and precision of devices and why is this important?

Accuracy is defined as the degree to which an alcohol interlock device can correctly and exactly measure the BrAC of a breath sample and precision is the degree to which this can be repeated with the same result.

It is crucial that devices accurately and precisely measure the BrAC of a driver in order to ensure an intoxicated driver is prevented from operating the vehicle and to prevent inaccurate BrAC readings from registering as a violation against a driver who has not had any alcohol.  

7.c) What is linearity and why is it important?

Linearity is the ability of the interlock device to accurately measure BrAC over a range of BrAC levels. Devices should be able to accurately measure from low BrACs to high BrACs. Of note, calibration at a higher BrAC level provides a more accurate measure as opposed to a calibration at .02, but testing must still be done at .02.

It is important for courts to be able to demonstrate higher BrACs are accurately measured, particularly if additional sanctions or penalties may be applied.

7.d) What is lab mode or metrological mode?

Lab mode or metrological mode is a mode in which the device is most apt for testing and should only be used for testing purposes by the designated agency. When a device is switched to lab mode it facilitates smoother bench testing by allowing for non-human test samples as well as repetition of tests in a shorter time period (e.g., instead of needing to wait five minutes for the device to reset, it can test again immediately).

8.a) What is field testing and why is it important?

Ideally, field testing is done prior to certification of the device as well as periodically after certification. For example, a jurisdiction may schedule annual field testing of devices. The purpose of a field test is to confirm that devices respond to events in accordance with administrative rule or statute. The purpose is not to test the accuracy of the device but instead ensure the device meets the jurisdiction’s required configuration profile(s). For example, to verify the device triggers a running re-test within five  minutes of the vehicle being started and at specified intervals thereafter. This encourages standardization of devices, ensures uniformity of programming, and helps to ensure that required device features are activated.

It is beneficial to have individuals responsible for operating the program, such as licensing staff, probation officers, treatment providers, and court officials participate in field tests. Criminal justice practitioners often do not have an opportunity for interaction with the device and, instead, only hear about the device through offenders. Their participation in the field testing allows for a rare chance to become familiar with the device and understand how it operates. This is especially relevant to those practitioners who are responsible for reviewing data logs and who will testify regarding violations.

Field testing can also assist in building relationships between vendors and state agencies through the provision of feedback. It is beneficial to keep vendors apprised of field testing and to make them aware of how their devices perform in relation to state standards/requirements. One strategy that can be utilized it to send vendors a checklist of what is being tested during field testing so that they are aware of expectations and of what standards need to be met. This is not meant to advise the vendors on how to set the devices being sent for field testing, but as a method of maintaining transparency with the manufacturer. Devices sent for testing should not be specially configured other than the normal configuration for that jurisdiction. Jurisdictions can also benefit from providing vendors with a checklist of requirements for the performance of devices because this clarifies the configuration profile as well as the language in statute or administrative rule thereby eliminating room for ambiguity and interpretation.

8.b) What does a field testing protocol generally entail?

As with device certification, one agency should be designated with the authority for and responsibility of field testing. It is essential that devices undergo field testing by a knowledgeable authority in order to confirm that devices are properly configured in accordance with the configuration profile outlined in administrative rule or statute. It is important that the person who is tasked with the testing of devices is well-versed in the technical aspects of interlock devices and the conditions that may influence testing.

The following tests can be included in a field test:

  • tests of non-alcohol products and food to determine if they produce false positives;
  • confirmation of various lockout scenarios;
  • attempts to use non-human breath samples;
  • disconnection of power;
  • test configuration profile/violations;
  • occurrence and timing of running retests;
  • test anti-circumvention features; and,
  • restart of stalled motor vehicle.

An example of a checklist which outlines ideal device performance can be found here.

The test protocol should include the creation of specific events to verify responses to re-test refusals, high-BAC fails, and circumvention attempts. The device should be installed in a state vehicle for whatever length of time is needed to test all device requirements (e.g., for example, 30 days would be too long and resource intensive). At least two state employees should be present when conducting the tests; one should take notes of events which can then be matched against responses logged by the device to measure accuracy. This process can also help staff in learning the terminology used by different manufacturers to describe different types of events. Employees should also document the process by taking pictures of the installation and de-installation of the device as well as the interior of the vehicle. If possible, a manufacturer representative should be invited to participate in the field testing by being present for a day of testing.

8.c) How frequently should devices be field tested?

The first field test of devices should occur within a few months of initial certification, but preferably a field test would be passed prior to certification. Frequent field testing should be conducted initially to confirm compliance to configuration profiles of devices that have failed testing. Once compliance is demonstrated, the frequency of field testing can be reduced. Agencies should keep in mind that annual field testing will contribute to raising program standards. If there are consistent complaints about a particular device or device modification, this should trigger further field testing. In general, a timeframe should be determined which respects the capacity and resources of the agency responsible for field testing; this can be outlined in administrative rule. If the program authority is regularly auditing data logs from interlock devices, this may minimize the necessity of field testing.

8.d) How should devices be selected for field testing?

It is important that device selection is random in order to ensure the selection is not biased. For instance, if the same device is continuously used for testing, there will be no room to discover glitches or bugs that may exist in other devices of the same model and version. Similarly, if a vendor is selectively providing a device for field testing, they may select a device that has been a greater level of attention and is not representative of all devices. This practice allows a vendor to effectively prevent the state authority responsible for testing from discovering potential device weaknesses or inconsistencies with the state configuration profile.

State agencies need to determine an efficient way to select devices at random, whether this involves going to the service center and selecting a device from the shelf or randomly selecting several serial numbers from a list and having the vendor send the corresponding devices. State agencies also need to determine the number of devices that will be submitted for field testing to ensure a wide breadth of testing balanced with resource limitations.

8.e) How can field testing be funded?

Collection of specific fees paid by service centers and vendors for licensing or fees paid by offenders for monitoring or interlock program participation (e.g., interlock restricted licenses) may be used to support the administration of the program including field testing and vendor oversight. Refer to Question 4a in the Implementation section for more information on opportunities to fund various components of interlock programs.

9.a) How can field testing be funded?

The following requirements should be adhered to by vendors when establishing and managing service centers within a jurisdiction. Specific expectations and requirements should be outlined for vendors to remove ambiguity in administrative rule or during the certification process; this level of oversight will help improve the quality of service delivery and also improve program integrity as it demonstrates a certain amount of due diligence on the part of the state.

  • Vendors should review the jurisdiction’s administrative rule and agree in writing to comply with these requirements.
  • Jurisdictions should require that vendors conduct background checks for service center technicians and any staff that has access to client data and/or interlock data. Service center staff should be required to sign confidentiality agreements that adhere to relevant jurisdictional laws.
  • Jurisdictions should review training and certification protocols employed by vendors. Vendors should affirm in writing that staff has received appropriate training about the jurisdiction’s interlock program. Jurisdictions may further require that service technicians undergo some form of testing or performance review process in relation to specific jurisdictional requirements. This testing can be undertaken by either a state agency or vender. This type of process helps the program authority maintain control over those who are approved to install and service interlocks and de-certify installers who fail to perform their job properly.  
  • Jurisdictions may wish to specify whether subcontractors may be used for the purposes of installation, device removal, or data downloads. If subcontractors are used, they should be held to the same standard as vendor employees as it relates to device servicing, calibration, and reporting. It would be the vendor’s responsibility to ensure that all contractors perform their duties in accordance with state rules and regulations as well as any internal quality protocols.
  • Service center staff should not have the ability to make any changes to the device software, configurations, or reports.
  • Vendors should inform the program authority about the selected locations for service centers. The program authority may choose to approve these locations. Criteria include:
    • service centers should be located within a reasonable distance from all potential clients throughout a jurisdiction (e.g., 50 or 65-mile radius);
    • service locations should have a licensed technician available during business hours;
    • separate waiting area for clients so they cannot observe installation;
    • clients do not have access to interlock or confidential client data on the computer;
    • separate area to conduct device training with participants and to review client documentation;
    • files and paperwork are secured in a locked filing cabinet to protect client information; and,
    • technicians should have access to a help desk that can respond to technical challenges that arise.
  • Vendors should ensure that all service centers possess all of the diagnostic and other equipment, tools, and replacement parts or complete units needed to assure device functionality.
  • Service centers should have liability policies and insurance and/or surety bonds to protect the jurisdiction in the event of service error or if locations are closed such that clients must find other service locations.
  • Service centers should meet all business zoning requirements and have a current business license on display.

9.b) How can jurisdictions address service center non-compliance?

To ensure that service centers adhere to state requirements, an inspection or audit protocol can be put in place as is practicable. Such a protocol should be developed with consideration of requirements contained in relevant documents such as administrative rule, technical standards, and the approval process or vendor contract. There are many elements to a service center audit (which are outlined in Alcohol Interlock Programs: Vendor Oversight) and key activities that should be considered during an inspection are detailed in Question 10b.

Service centers should be officially notified of the reasons they are non-compliant and given a timeframe to resolve any identified issue(s) before sanctions are imposed. Manufacturers should also be alerted about service center issues as they are best positioned to address the problem with the service center. Furthermore, manufacturers benefit from ongoing feedback in relation to their performance and quality of service delivery within a jurisdiction as it provides them with insight into issues at an operational level and an opportunity to improve.

The program authority should have a de-certification process in place to effectively manage vendors or service centers who fail to comply with state rule and regulations. The de-certification of manufacturers or service centers to prevent them from doing business in a jurisdiction should not be undertaken lightly as this can inconvenience clients and disrupt service delivery. For this reason, it is recommended that jurisdictions have in place a series of graduated sanctions that may be applied to strongly encourage manufacturers, vendors, and service centers to be compliant.

Jurisdictions that have oversight experience note that most manufacturers and service centers are willing to comply with requirements and should have a reasonable opportunity to demonstrate compliance before they are no longer permitted to provide services in a jurisdiction. In particular, the suspension or removal of a vendor can have profound implications for program participants who must have new devices installed, and can negatively affect available service locations throughout a jurisdiction. For this reason, jurisdictions are encouraged to consider a range of options (e.g., suspending new installations, imposing fines) designed to bring manufacturers and/or service centers into compliance so that the removal of a vendor is only considered as a last resort.

Consideration should also be given to whether service centers will be able to appeal the imposition of sanctions, how this process will be managed, and by which agency.

10.a) What is calibration?

Calibration is a process by which a tester uses an alcohol reference sample to determine if an interlock device accurately measures the BrAC of a user. If the device is not accurately measuring the BrAC, the device can then be adjusted or re-calibrated to ensure the correct measurement of future samples.

Other important aspects of calibration in relation to interlocks include:

  • Calibration interval. As defined by the Association of Ignition Interlock Program Administrators (AIIPA), the calibration interval is the maximum time period that an alcohol interlock may be used without a calibration check, after which the ignition of the vehicle must lock.
  • Calibration stability. The ability of an alcohol interlock to hold its correct calibration over a defined time period.
  • Service interval. The maximum time period that an alcohol interlock may be used without maintenance or data download, after which the device must be serviced or the ignition of the vehicle will lock.

10.b) What is the difference between wet bath and dry gas calibration? What are the issues associated with each method?

There are two common methods used to calibrate interlock devices: wet bath and dry gas. A simulator is a device that produces an alcohol-in-air test sample of known concentration (e.g., a Breath Alcohol Sampling Simulator BASS)) or a device that meets the NHTSA Model Specifications for Calibrating Units (72 FR 34742). NHTSA has a conforming products list (CPL) for simulators (2012-0063) which can be found at: www.gpo.gov/fdsys/pkg/FR-2012-10-22/pdf/2012-25915

Wet bath. A wet bath simulator is an electronic, temperature controlled instrument that, when used with alcohol reference solution, will provide precise and accurate calibration standards with alcohol breath instruments. This type of simulator is used because it provides the ability to closely replicate a human breath sample.

There are many details that must be attended to which, if ignored or misunderstood, could cause inaccurate interlock calibration. The most common errors occur as a result of:

  • incorrect temperature of alcohol reference solution;
  • air leaks in the simulator;
  • incorrect connection or poorly maintained connections from simulator to interlock device;
  • impotent alcohol reference solution;
  • improper maintenance of equipment; and,
  • ineffective training of technicians.

Solutions for simulators may be on the above referenced NHTSA CPL or could be specified by state regulation as being on an approved list.

Dry gas. The dry gas method requires the introduction of a pressurized dry standard gas, which has a specified concentration of alcohol, into the interlock device and compares the resulting BrAC reading with the corresponding alcohol percentage in the dry gas mix.

The over-arching benefit of using a dry gas simulator as opposed to a wet bath simulator is the reduced chance of calibration errors. Dry gas is generally a more stable solution, is easier to use, and lasts longer than the solution used in a wet bath simulator. However, the dry gas simulator must also be operated and maintained correctly to ensure accurate calibrations. The most common issues that can cause inaccurate functioning are:

  • temperature and humidity of environment in which the cylinder is stored and used;
  • failure to factor in the effect of high altitude on testing;
  • improper or unclean tubing connections; and,
  • ineffective training of technicians.

How to determine whether calibration is done properly.

The observation of device calibration is an important aspect of vendor oversight. While it may be challenging to control for improper calibration if the program authority lacks resources and staffing to conduct service center audits/visits, this is something that jurisdictions can work towards and begin to do on a limited basis. The collection of various program fees (outlined in Question 4a of the Implementation section and Question 8e of this section) can help fund these types of oversight initiatives.

When observing the use of wet bath simulators, particular attention should be given to the simulator model and serial number, the date of last calibration of the wet bath simulator, the temperature reading on the device, the tubing connections, cleanliness of the device, the age and usage number of the reference solution, the temperature of the ambient air, and the measuring of the reference solution used.

A checklist for verifying that wet bath simulators are used in accordance with standard practices should include the following:

  • observe the environment temperature and location before calibration is initiated (e.g., is the solution exposed to direct sunlight);
  • check the temperature of the reference solution;
  • note when the reference solution has been changed, the dates on the bottle, and where it is stored at the service center;
  • check that tubing is properly connected;
  • check that there is a lack of moisture in the tubing;
  • check the cleanliness of the device (i.e., cleanliness of connections and lack of algae in the glass cylinder);
  • observe a calibration process and ensure proper operation;
  • interview persons using calibration devices to verify where the calibration unit is stored when not in use and how the calibration equipment is used and maintained; and,
  • check to verify that technicians were given proper training, have manuals to refer to, and that they are in compliance with service center requirements outlined in administrative rule or statute.

The observation of dry gas simulators should include checking the tubing connections, the length of tubing, the age of the cylinder, the temperature of the ambient air where the cylinder is stored and used, and the altitude conversion if needed.

A checklist for verifying that dry gas simulators are used in accordance with standard practices should include the following:

  • check the length of tubing;
  • check to ensure that there are proper and clean tubing connections in place;
  • observe the storage of the cylinder and temperature of the environment;
  • check the date on the cylinder (which should be located on the ‘Certificate of Analysis” that should be attached to the tank of gas);
  • observe a calibration process and ensure proper operation;
  • interview persons using calibration devices to verify where the calibration unit is stored when not in use and how the calibration equipment is used and maintained; and,
  • check to verify that technicians were given proper training, have manuals to refer to, and that they are in compliance with service center requirements outlined in administrative rule or statute.

The training of technicians is of vital importance to ensure that calibration is done properly. It is for this reason that it is imperative to speak with service center technicians and to observe them during the completion of their duties.

Inspectors should have a checklist of what to look for when they visit a service center that contains many of the points listed above. For an example of such a checklist, please refer to these Illinois forms: dry gas checklist, wet bath checklist, service center questions.

11. What is the difference between alcohol interlock and evidential breath testing devices?

Breath tests on an interlock device involve a breath testing procedure that is controlled by the end user and is not an evidential quality test. The procedure is different in that there is not necessarily a deprivation period of 15 minutes (although users are advised during the installation and training to wait to avoid false positive tests due to mouth alcohol), there is no calibration check, and the breath tests will administer a pass, warn or fail, with no immediate second test.

Conversely, evidential breath tests are managed and collected by law enforcement. There is often a deprivation period of at least 15 minutes as part of established breath testing procedures to avoid false positive breath tests that can result from mouth alcohol. The breath testing instrument performs an air blank, a calibration check, more air blanks and multiple subject tests separated in time before reaching a result.

It is also underscored that alcohol interlock devices are not used for the same purpose as evidential breath testing devices. As such, alcohol interlocks are not required to meet the same legal standard as the evidential breath test that occurs when drivers are stopped by police and/or arrested for impaired driving.

Typically, an evidential breath test is used in criminal DWI trials. In these trials, the burden is always on the prosecution to prove the case beyond a reasonable doubt.  Therefore, an evidential breath testing device is subject to a number of challenges under the Rules of Evidence. In cases involving ignition interlocks, the tests are more likely to be part of an impaired driving post-conviction legal proceeding. The legal burden is much simpler; it is a preponderance of the evidence and the Rules of Evidence do not apply. However, the evidence must still be able to be proven reliable.

When the Rules of Evidence apply, the prosecutor may have to prove the validity of the evidential breath test, including the scientific foundation of the device. This could also be necessary in a post-conviction hearing, but the proof of validity may not be as stringent. The level of validation needed will rely on the jurisdiction and the individual judge for each case.

Program administrators should be prepared to testify on the scientific principles of the device and the demonstrated accuracy of the device. However, it will depend on the judge in each individual case as to who can provide acceptable testimony on the science of the device and device testing. Programs should have specific and detailed quality assurance plans to provide proof to the courts that a specific device was installed and operating properly. The plan should include records as to the maintenance and calibration of devices, field testing results, lab testing results, installer training and qualifications and inspections of service centers.

It is equally important as part of judicial education activities to ensure that judges are aware that, while interlock devices are not used as an evidential test for the purposes of post-conviction court proceedings, the devices are subject to the most recent NHTSA model specifications for devices as well as any technical standards described in administrative rule, and a certification process. Similarly, judges should be informed about:

  • how devices function;
  • the standard that devices must meet in order to be certified in a jurisdiction;
  • the process by which devices are certified by a jurisdiction; and,
  • the state agency that oversees the certification for the devices. 

12. What types of legal challenges to interlock devices should be expected?

There are a variety of legal challenges that alcohol interlock devices may encounter. The above section is likely the biggest legal challenge a program may face: showing that the device is based on a valid scientific principal, that the principal was properly applied in this particular device, and properly used in a particular instance. Program administrators should be prepared to answer challenges based on the specific installer, installation procedures, calibrations, calibration equipment, documentation and, in jurisdictions where cameras on not used, who actually submitted the breath sample on the device.

Program administrators may receive either subpoenas or freedom of information requests in relation to the functioning of the interlock device and/or the information collected by it. Program administrators should have a good understanding of who owns the information or data that is being requested and who has authority to release it. In addition, they should also be aware of any implications associated with the provision or release of this information and data.

Programs should have a very specific quality assurance plan that will demonstrate that the manufacturers, vendors and service centers are qualified and supervised.  The plan should also provide assurance that devices are properly certified, tested and maintained. The program should have staff that can attest to the functioning of the devices and how the quality assurance plan is applied.  

13.a) What types of documentation do program administrators need to demonstrate that devices were operating properly?

There are many types of documentation that program administrators should be familiar with in order to be able to demonstrate that devices were properly functioning for the purposes of inquiries and/or legal proceedings.

It can be very useful for program administrators and/or agency staff to have available examples of forms and agreements that are routinely used by vendors or service providers in order to facilitate efficient responses to inquiries. These may include copies of service agreements, customer contracts, reporting formats, identifiers for clients, copy of the training materials that the client receives, and any forms or waivers that clients may have signed as part of the service or lease agreement.  

In addition, it is important that program administrators are familiar with the general operation of service centers as it relates to devices and this may even include speaking with technicians at service centers to ensure understanding of the process that is utilized. For example:

  • Do administrators have confirmation from manufacturers or vendors that service center technicians and associated staff received training as part of the certification process?
  • Is there documentation to demonstrate that the technicians have successfully completed any certification of technicians by the state authority (see Oklahoma) or other third party?
  • What is the standard used for the training of technicians?
  • Have technicians been subject to a criminal background check?

Similarly, administrators should be knowledgeable about the availability of calibration logs for devices from service centers and are able to ensure that the results of calibration are noted in the log.

13.b) How do program administrators ensure data security?

Ideally, jurisdictions will have the ability to implement an automated data system which allows manufacturers or vendors to send, and the monitoring authority to receive, information electronically and for each to store it in their own protected system. The benefits of automated data management and an overview of steps to take to move to an automated system can be found in (Alcohol Interlock Program: Data Management System Implementation.)  In particular, programmers who devise an automated system must be educated about the sensitive nature of the data being communicated so that the system includes built-in security measures for data transmission and storage. Program administrators may further require manufacturers or vendors to send data in a specific format and obtain acknowledgement that they are doing so.

The most rigorous example of data management is found in The Netherlands where the protection of personal data is regulated through the government per the Dutch Privacy Act. National requirements regarding the protection of personal data have been established which mandate that vendors must create a protection file that meets specific requirements. Vendors are not approved to do business until the protection file meets minimum standards.

It is important that manufacturers or vendors are able to demonstrate and attest to the security of the data from the device and that program administrators are notified in relation to documentation regarding approved employees who, at the vendor and service center provider5 level, have access to the data, who have the ability to alter or change that data, and understand how the vendor ensures the integrity of the data.

The security and protection of data is an essential priority for programs. As such, designing programs to ensure participant privacy must be balanced with requests and requirements to share certain information. To illustrate, program administrators or staff may often be asked to supply information about the program in general, and/or to provide specific information about program participants and their device records. These requests may come from other agencies in the jurisdiction also tasked with managing a segment of the alcohol interlock program, in the form of a subpoena, court order, or a Freedom of Information Act (FOIA) request, and, less formally, directly from program participants, attorneys, the media and the general public.

Court orders or subpoenas can result from both criminal and civil court proceedings. It is not uncommon, for instance, for courts to subpoena violation reports and BrAC readings in probation revocation hearings, traffic court hearings, or cases involving child custody. Program administrators need to be aware of what information legally has to be provided and the ramifications for not providing it. For instance, failure to respond to a subpoena or court order can be considered civil contempt and is punishable by fines, conditions and jail time. FOIA requests are also mandated in some instances. In addition, administrators should also be familiar with the types of program documents and information in their program that may be subject to FOIA.

Releasing information in any situation other than a court order, subpoena or FOIA request is not recommended without written consent from the program participant. To limit liability, programs should have written policies and procedures to guide the release of information and all requests should be directed to a single individual in the program, preferably legal counsel. To protect the program participants’ legal rights to privacy, legal counsel should also be consulted as to what documentation must and can be released, if any, in response to each specific type of request and included in the policies and procedures.

5 Service center provider is defined as the entity designated by the manufacturer to provide services to include, but not limited to, installation, monitoring, maintenance, and removal of the alcohol interlock device.

14. How can jurisdictions ensure their procedures/protocols protect them against legal challenges?

It is imperative that alcohol interlock programs have detailed procedures and protocols in place so that any component of the program that is potentially called into question is proven reasonably designed and is defensible. To help ensure that program procedures and protocols are comprehensive and address any challenges that may arise, administrators should have legal counsel on staff, or from whom they can seek consultation and review of the practices that are implemented. In addition, administrators and staff should spend time with legal counsel to become well-informed about the program, the devices and any potential challenges. To this end, program administrators can refer to the issues raised in Question 12 as a foundation to begin to develop procedures or protocols that are supported by appropriate documentation and research. Efforts are also needed to ensure that these procedures and protocols are closely adhered to by staff. 

As noted previously in Question 13b, it is very useful to consult legal counsel to be fully informed regarding what documentation must be released in response to a subpoena or a FOIA request and what should or should not be released in response to a request from the program participant. Similarly, the identification of key experts and appropriate program staff who are knowledgeable and can attest to certain aspects of the program and device function and assist in providing testimony is also useful to create efficiencies and consistency in such matters. Key topics for consideration include:

  • device testing lab
  • field testing and device certification
  • manufacturers of the BAIID and the calibration equipment
  • physiology of alcohol in the body and BAC readings
  • data downloads and data storage

As a final note, there should be one or two persons designated within the interlock program to handle requests for information and legal mandates in order to maintain consistency and ensure accountability.

Without well performing devices, a program cannot operate at an optimum level. Jurisdictions should have a process in place to ensure an interlock device meets NHTSA model specifications as well as the device requirements for that jurisdiction. Frequently, jurisdictions rely on the lab test report to confirm that an interlock should be used in their program. Lab tests are necessary and should be required in a program, however, lab results should not be relied upon as the sole method of device testing and certification.  It is critical that programs understand device function, operation and the implications of device modification. For these reasons, the development and use of a field testing protocol is important as it provides program administrators with valuable information as to whether approved devices are, in fact, functioning as required. Additionally, programs should be aware of and understand the legal implications and questions that may be arise with interlock devices and their functionality. Establishing an effective and thorough certification process will create a more program and provide for accountability for device operations and subsequent readings.


Without well performing devices, a program cannot operate at an optimum level. Jurisdictions should have a process in place to ensure an interlock device meets NHTSA model specifications as well as the device requirements for that jurisdiction. Frequently jurisdictions rely on the lab test report to confirm that an interlock should be used in their program. Lab tests are necessary and should be required, however, lab results should not be relied upon as the sole method of device testing and certification.  It is critical that programs understand device function, operation and the implications of device modification. Additionally, programs should be aware of and understand the legal implications and questions that may be arise with interlock devices and their functionality. Establishing an effective and thorough certification process will create a more robust program and provide for accountability for device operations and subsequent readings.