What is an ignition interlock device ‘lockout’?

Legally Reviewed by Shazam Kianpour on August 31, 2026

An ignition interlock “lockout” happens when the device detects alcohol on your breath at or above a set legal threshold and temporarily prevents your vehicle from starting. In Colorado, that threshold is a breath alcohol concentration of 0.025, and the consequences of repeated lockouts can follow you well beyond the original interlock requirement handed down after a DUI or DWAI case.

Our Denver DUI defense team regularly represents clients who are managing a Colorado interlock restriction and want to understand exactly what a lockout is, how it is reported to the Department of Revenue, and what happens if the reports start to add up. If you are already dealing with an interlock requirement and want to know how long that requirement lasts in the first place, we cover that separately in our detailed breakdown of Colorado interlock duration rules. This article focuses on the lockout event itself, the 0.025 threshold, and the DMV hearing process that follows repeated violations.

How an Ignition Interlock Device Works

An ignition interlock device, or IID, is a breath testing unit wired directly into your vehicle’s ignition system. Before the car will start, you have to blow into a handheld sensor connected to the device. If the sample shows no measurable alcohol, or a level below the device’s threshold, the vehicle starts normally. If the device detects alcohol above the threshold, it blocks the ignition and logs the failed attempt.

Most interlock providers also require rolling retests once the vehicle is running, prompting the driver to blow into the device again at random intervals during a drive. A failed rolling retest does not shut off the engine while you are driving, but it is recorded the same way an ignition failure is, and it becomes part of the same monthly compliance report your provider sends to the Colorado Department of Revenue.

What Counts as a Lockout Under Colorado Law

Not every failed breath sample is treated as a reportable lockout. Colorado defines a lockout as any instance where the device detects alcohol at or above 0.025 and, as a result, prevents the vehicle from starting. This threshold is meaningfully lower than the 0.08 blood alcohol standard used in a typical DUI case, which is intentional. The interlock program is designed to catch any detectable drinking, not just impairment-level drinking, since the entire point of the restriction is abstinence while driving on an interlock-restricted license.

A single lockout on its own does not usually trigger a DMV action. According to interlock manufacturers, a first-time lockout typically requires only a short waiting period, often just a few minutes, before you can submit another breath sample and start the vehicle if that second sample passes. The stakes change considerably when lockouts start recurring.

The Three-Lockouts Rule and What It Triggers

Under Colorado’s interlock regulations, if your provider reports that the device registered a lockout in three separate reporting months within any twelve consecutive months, the Department of Revenue can extend your interlock restriction. The extension can add up to one additional year onto whatever period you were already required to drive with the device installed.

A few details matter here that are easy to misunderstand. The three qualifying months do not need to be back to back. They simply need to fall within the same rolling twelve-month window. And the trigger is not three individual failed breath samples in one sitting. It is three separate monthly reporting periods in which at least one lockout was recorded. A driver who has one bad month, then several clean months, then another bad month eight months later can still fall inside the same twelve-month window and face an extension if a third reporting month occurs before the window closes.

The Department of Revenue also treats evidence of tampering or circumvention of the device as a separate, and often more serious, category of violation, distinct from a standard lockout based on breath alcohol content.

Requesting a DMV Hearing to Contest an Extension

When the Department of Revenue notifies you that your interlock restriction is being extended, you are not required to simply accept that decision. Colorado law gives interlock-restricted drivers the right to request a hearing with the Colorado DMV before the Motor Vehicle Hearings Division to contest the extension. Requesting a hearing promptly can, in many cases, postpone the effective date of the extension until after the hearing officer reviews your case.

At an interlock extension hearing, the sole issue before the hearing officer is narrow: whether lockouts actually occurred in three of the twelve consecutive reporting months the Department relied on, and if so, how long the resulting extension should be. This is a more limited proceeding than a full DUI hearing, but it is still a real opportunity to challenge the underlying reports rather than simply absorb another year of interlock obligations.

You can request copies of the lockout reports the Department is relying on before your hearing date, which lets you and your attorney review the specific dates, times, and readings the provider submitted. If you do not request a hearing, the extension generally proceeds as reported.

Evidence That Can Matter at an Interlock Hearing

Ignition interlock devices are sensitive instruments, and the readings they produce are not always a clean measure of alcohol consumption. Several categories of evidence commonly come up when a driver disputes a reported lockout, including the following:

• Device calibration records. Colorado requires interlock providers to calibrate and service devices on a regular monthly schedule. A device that was overdue for calibration or serviced improperly can produce unreliable readings.
• Mouth alcohol and residual alcohol sources. Certain mouthwash, breath spray, cough syrup, and even some foods can leave trace alcohol in the mouth that a breath sample picks up as a false positive, separate from any alcohol actually in the bloodstream.
• Provider reporting errors. The report itself may misstate a date, a reading, or a sequence of events, which can only be caught by comparing it against the device’s own data log.
• Circumstances around the sample. Whether a rolling retest was refused because the driver was actively driving in traffic, or whether an ignition attempt reflects a passenger rather than the restricted driver, can also be relevant.

None of these categories guarantees a particular outcome at a hearing, and a hearing officer may still find that a reported lockout stands. What they illustrate is that a lockout report is a claim by the device and its provider, not an automatic, unreviewable fact, and Colorado’s hearing process exists specifically so that claim can be tested.

Why the Lockout Threshold Is Set Where It Is

The 0.025 threshold reflects the underlying philosophy of the interlock program. A restricted driver is not being held to the 0.08 impairment standard used to charge a DUI in the first place. Instead, the restriction assumes zero tolerance for any detectable alcohol while driving on an interlock-restricted license. This is why even a level well below what would ever support a new DUI charge can still register as a lockout and, if it repeats, can extend the length of time you are required to keep the device installed.

This distinction matters when clients ask whether a lockout means they were legally impaired. It does not. A lockout is a compliance event tied to the interlock program’s own threshold, not a finding that a new DUI occurred. The consequences run through the DMV’s administrative process, not the criminal courts, though the two systems can intersect if a lockout coincides with other conduct that draws law enforcement attention.

How We Can Help With an Interlock Lockout Issue

Our firm has spent years handling DUI defense and DMV hearings for clients across the Denver metro area, and we understand how quickly an interlock extension notice can upend plans you had already made around when your restriction was supposed to end. We review the lockout reports the Department is relying on, look for calibration and reporting issues, and represent clients directly at Motor Vehicle Hearings Division proceedings.

If you have received notice of an interlock extension, or you are trying to understand what a recent lockout might mean for your case, do not wait until the response window closes. Our team can review your reports, explain your hearing options, and help you decide how to move forward. Contact Shazam Kianpour & Associates, P.C. through our online form to discuss the specifics of your situation.

Frequently Asked Questions About Ignition Interlock Lockouts

Written by

Shazam Kianpour

Denver Criminal Defense Attorney & Founder, Shazam Kianpour & Associates, P.C. — Over 10,000 criminal and traffic cases handled across Colorado.