Many of the reasons ignition interlocks fail to measure BACs have nothing to do with drinking and driving. A program fails a driver because a required calibration appointment is not kept, a lockout for “mouth alcohol” resulting from cough syrup is not cleared within 15 minutes, or for a variety of reasons the data log is not transferred completely to the monitoring authority. Services around the interlock device are what determine whether or not a driver is able to complete his/her program of supervision on time.
For service providers, probation officers and defense attorneys representing clients on a DUI case, it is more helpful to understand where compliance actually breaks down rather than reading another explanation of how a handheld ignition interlock device works.
Installation decisions that shape the next twelve months
However, a good installation is not only important to prevent false negative events (e.g. Due to voltage drop during crank) but also negative events that are attributed to the technician’s mistake. Before installing the ignition interlock, a good service provider should identify potential problems that could occur as a result of a vehicle’s specific characteristics (e.g. Push button start, start/stop for fuel efficiency purposes, aftermarket car alarms that interfere with the ignition interlock’s power cable).
The documentation of an install is just as important as the wiring. This includes photos of the install, the mileage on the vehicle at the time of installation, the serial number of the device installed, the location of any seals on the drawpipe, and the VIN# of the vehicle it was installed in. These photos and documents create a paper trail of what happened at the time of installation and can be used to prove that a tamper event was caused by a technician error and not by the client.
Matching the device to the program conditions
Not all ignition interlock cases are created equal. It matters what a particular court has ordered, and specifically whether the case requires installation of a camera, verification photos, GPS and mapping of where a driver was when a violation occurred, and/or real time reporting to probation and/or monitoring authorities.
Calibration intervals and why drift is the quiet risk
The main issue with fuel cells is that they can “drift” and that most states require a device to be calibrated every 30-60 days. This is something that the device monitors and that sets a service reminder (usually 7-10 days prior to the next required service) that starts a countdown. At the end of the countdown the device locks up permanently.
Staying on track with interim services for traveling, shift workers and those living miles from centers can help in avoiding lockout recoveries. Scheduling the next visit prior to the client leaving the center, sending reminders out 7 and 2 days prior to the visit and offering evening and weekend appointments where possible can help in this respect. Drivers under a state-ordered program are usually better off working with a provider that handles car breathalyzer services in Virginia daily, because familiarity with local calibration windows keeps appointments from slipping past the deadline.
| Service event | Typical interval | Primary compliance risk if missed |
| Calibration and data download | 30 to 60 days | Permanent lockout, reported violation, tow charges |
| Device inspection for tamper | At each calibration | Undetected circumvention finding at program end |
| Firmware or configuration update | As released | Reporting format rejected by monitoring authority |
| Lease renewal and documentation | Per program term | Gap in coverage, treated as non-installation |
Testing behavior and the failures that are not drinking
Even more significant than preventing alcohol-impaired driving is preventing the false guilt of someone operating his/her vehicle while having mouth alcohol from items such as mouthwash, breath sprays, energy drinks, etc. Typically these readings decrease to a 0.000% within 15 minutes.
Many of the missed retests for rolling retests occur when a driver does not hear the prompt over road noise, pulls into a parking garage, or even has another person breathe for the client (e.g. A spouse). This issue is best addressed through coaching the client at install and again at the client’s first calibration.
What to teach in the first ten minutes
- Wait fifteen minutes after eating, drinking, or smoking before any test
- Pull over safely for a rolling retest rather than attempting it in traffic
- Never allow another person to provide a sample, including in an emergency
- Report mechanical or battery issues before disconnecting anything
- Keep the service appointment card in the glove box with the lease agreement
Maintenance, reporting, and the handoff to monitoring authorities
Also of critical importance, errors in reporting cases to the court, DMV or probation department (or relevant monitoring authority) in multiple ways can create client problems with no connection to their behavior. All such errors are recorded against the client.
How professionals add value to monitor service for drivers. Reconciling the submissions log against the confirmations from the monitoring authority in days (not months) will identify any missing reports for a client before they become issues for a hearing. Know who your data is being sent to, how often, and ask for a copy of the data submitted for you.
Closing out the program
Removal of an Ignition Interlock Device (IID) typically requires a written request for early removal from all jurisdictions in which the individual is on probation and written confirmation of early removal from the service provider. The provider should retain all service history for the statutory time period (typically 5 years). Although the end of the lease term may appear on the face of the contract, early removal will almost certainly cause the remaining term to ‘retrigger’ unless carefully confirmed in writing prior to disconnection and removal of the IID.