If you have a restricted license with an ignition interlock device in Michigan, a failed breath test can feel like a devastating setback. But a failed test does not automatically mean you will lose your license. Understanding what happens next — and acting quickly — can make the difference between keeping your restricted license and starting the restoration process all over again.
How the Interlock Device Works
An ignition interlock device (IID) is a breathalyzer installed in your vehicle that requires you to provide a breath sample before the engine will start. Once you are driving, the device will also prompt you to provide “rolling retests” at random intervals to ensure you remain sober while operating the vehicle.
The device records every breath sample, every start attempt, and every rolling retest. This data is downloaded at regular service appointments and reported to the Michigan Secretary of State. Any anomalies — including failed tests, missed tests, or skipped service appointments — can trigger a violation.
What Triggers an Interlock Violation?
The most common interlock violations in Michigan include:
- Failed startup test — A breath sample that registers above the device’s BAC threshold (typically 0.025)
- Failed rolling retest — A positive reading while the vehicle is in operation
- Missed rolling retest — Failing to provide a breath sample when prompted
- Missed service appointment — Not bringing the vehicle in for data download on schedule
- Tampering or circumvention — Any attempt to bypass, disconnect, or manipulate the device
- Vehicle operation without the device — Driving a vehicle that does not have an interlock installed
What Happens After a Failed Test
When the interlock device records a violation, the data is transmitted to the Secretary of State at your next service appointment. The Secretary of State will then:
- Review the data — The Secretary of State examines the device logs to determine if a violation occurred
- Issue a notice — If they determine a violation occurred, you will receive a notice of a violation hearing
- Schedule a hearing — You will be given a date to appear before the Office of Hearings and Administrative Oversight (OHAO)
- Hearing decision — The hearing officer will determine whether the violation warrants revocation of your restricted license
Common Causes of False Positive Interlock Tests
Not every failed interlock test means you were drinking. False positives are more common than many people realize. Known causes include:
- Mouthwash and breath fresheners — Many contain alcohol that can trigger the device
- Hand sanitizer fumes — Using hand sanitizer immediately before testing can cause elevated readings
- Certain foods — Fermented foods, ripe fruit, bread, and some energy drinks can produce trace amounts of alcohol
- Medications — Cough syrups, cold medicines, and some prescription medications contain alcohol
- Temperature and humidity — Extreme conditions can affect device calibration
- Device malfunction — Like any electronic device, interlocks can malfunction or lose calibration between service appointments
How to Defend Against an Interlock Violation
If you receive notice of an interlock violation hearing, do not assume you will automatically lose your restricted license. There are several effective defenses:
- Challenge the data — An attorney can analyze the device data logs to identify patterns consistent with false positives rather than actual alcohol consumption
- Present independent testing — If you obtained a PBT or ETG test shortly after the failed interlock test, negative results can support your defense
- Document environmental factors — Evidence of products you used, foods you ate, or medications you took near the time of the failed test
- Device maintenance records — Show that the device was due for service or had a history of calibration issues
- Witness testimony — People who were with you and can confirm you were not drinking
The Stakes: What You Could Lose
If the hearing officer finds the violation was caused by alcohol consumption or intentional misconduct, your restricted license will be revoked. This means you would need to restart the entire license restoration process from scratch — including a new waiting period, a new substance abuse evaluation, new letters of support, and a new hearing. The consequences of an interlock violation are severe, which is why having experienced legal representation at your hearing is critical.
Act Quickly — Time Is Limited
If you have received notice of an interlock violation in Michigan, do not wait. The hearing will be scheduled quickly, and you need time to gather evidence and prepare your defense. Attorney Brandon McNamee has successfully defended hundreds of interlock violation cases across Michigan. Contact McNamee Law at (810) 982-2020 for an immediate consultation.
Frequently Asked Questions
Will one failed interlock test cause me to lose my license?
Not necessarily. A single failed test triggers a review, but the hearing officer will consider all the circumstances, including whether the failure was likely caused by alcohol or an innocent factor like mouthwash or food.
Should I get a separate breath or urine test after a failed interlock reading?
Yes — if possible, get an independent PBT or ETG test as soon as possible after a failed interlock reading. A negative result from an independent test is powerful evidence in your defense.
Can I drive while my interlock violation hearing is pending?
In most cases, yes. Your restricted license typically remains valid until the hearing officer makes a decision. However, you must continue to comply with all interlock requirements during this period.
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