A violation on the interlock: what counts, and what follows
Most people arrive here having just blown a number they did not expect, wanting to know how much trouble they are in. The short answer is that one reading is rarely the problem. What turns a bad reading into a violation is usually what happens in the next five minutes.
Would an interlock say failed with one drink?
A reading that is not drinking
Alcohol left in the mouth reads high for a few minutes and has nothing to do with what is in your blood — mouthwash, some medicines, and certain foods will do it. Programs account for this rather than ignore it. The District of Columbia does not count an attempt above 0.020 as a violation if a reading within five minutes comes back below it. Colorado excludes false results caused by mouth alcohol from what it counts. Vermont lets the Commissioner disregard a reading of 0.04 or above where a pattern of tests shows it does not indicate drinking.
Which gives the practical rule: wait, rinse with water, and blow again inside the window your program allows. What turns a bad reading into a violation is usually the retry that follows it, or the decision to walk away and drive something else.
A fail is not a violation, and the words come from different places
The device blocking a start is an event on your report. A violation is a finding by the agency that supervises you. Colorado says this outright: interlock companies use the word "lockout" too, but it is not the same as the legal definition, and the department is judging breath-alcohol events rather than whatever the vendor labeled them. The practical difference is arithmetic — a single event above the threshold is a fail, and in Colorado it takes such events in three separate months out of twelve before anything happens to your term.
Source: Colorado Department of Revenue, interlock hearings, checked 2026-08-30
A line on the vendor’s report is a record of what the device did. Whether it becomes a violation is a decision someone else makes later, using their own definition and their own counting rule.
Which is why panic on receipt of a report is usually premature — and why ignoring three of them is not.
What causes a violation on an ignition interlock?
Programs differ in the detail, but the same six turn up everywhere. Note how few of them involve drinking.
Trying to start above the threshold
The number is lower than any drunk driving limit — New Hampshire counts an attempt above 0.025, the District of Columbia above 0.020. This is the ordinary morning-after event, and it is why the device catches people who are certain they are sober.
Missing a rolling retest
The device asks again while you drive. New Hampshire requires the first retest 5 to 15 minutes after starting, then every 15 to 45 minutes. Not answering is itself a violation — it is treated as an unmonitored trip, not as a technicality.
Driving something else
Operating any vehicle without a device is a violation in every program we checked, and one of the heaviest. In New Hampshire it alone can add two years.
Blocking the camera
New Hampshire defines tampering to include any act that stops the camera taking a clear photograph identifying the driver. A hand, a sticker or a bad angle is not a defense — it is the violation.
Missing a service appointment
Colorado requires an inspection at least every 60 days and suspends the license of anyone who does not show up. New Hampshire locks the vehicle out five days after a missed calibration. The car stops working before anyone writes to you.
Taking the device out early
Removal without written authorization is a violation on its own, separate from anything the device recorded. The District of Columbia treats voluntary withdrawal from the program as a further year of revocation.
How many times can you fail an interlock test?
The difference between these is not severity but arithmetic. Some states add time per event; others ignore single events and act on a pattern.
| State | How it counts | Detail and source |
|---|---|---|
| Colorado | Three months out of twelve | A single failed start is not what ends you up at a hearing. Colorado counts months: a reading of 0.025 or more in three of any twelve consecutive months extends the interlock requirement by up to a year, and it can be extended more than once. The state publishes what the hearing officer weighs — and one of the listed mitigating factors is a single event where the driver did not try to start again. Which is the practical advice: after a fail, stop. Colorado Department of Revenue, interlock hearings · C.R.S. § 42-2-132.5; 1 CCR 204-30 Rule 11 · checked 2026-08-30 |
| District of Columbia | A fixed ladder, and a five-minute reprieve | The District adds 60 days for a first violation, 90 for a second and 120 for each one after that, on top of the original term — or removes you from the program altogether. It also publishes the rule that answers the most panicked question in this whole subject: an attempt above 0.020 is not a violation if a later reading within five minutes comes back under 0.020. DC DMV, IID program violations and penalties · 18 DCMR § 311.13, § 311.14 · checked 2026-08-30 |
| Vermont | Three events, three months added — and pull over | Vermont extends the wait for reinstatement by three months for every three recorded readings of 0.04 or above, and by six months for a single random-retest reading at 0.08 or above. It also requires something the other states leave unsaid: after failing a random retest you must pull over and switch the engine off as soon as practicable, and not doing so is a criminal offense. Vermont Statutes, 23 V.S.A. § 1213 · 23 V.S.A. § 1213(f), (g) · checked 2026-08-30 |
| New Hampshire | A hearing, then an extension | New Hampshire routes every alleged violation to an administrative hearing and extends the order for each occurrence found. The rules enumerate what counts, and driving a vehicle without a device carries the heaviest extension of the list. New Hampshire administrative rules, Saf-C 6500 · Saf-C 6509.01, 6509.02; RSA 265-A:38-a · checked 2026-08-30 |
The device is built to be argued with, and it wins
Everything the device sees is stored and sent on: the reading, the time, and in most programs a photograph of whoever provided the sample. New Hampshire treats obscuring that camera as tampering in its own right, so the workaround and the cover-up are the same offense. The report reaches the monitoring agency whether or not anybody tells you it has. That is the part people misjudge — not the chance of being caught in the moment, but the fact that the record arrives later, complete, and without you in the room.
And legally it is not the same thing as a failed test at all. A bad reading is handled by a hearing officer. Getting round the device is a criminal offense with its own charge, and the states that write it out are unusually specific about the methods:
| State | What it is | Detail and source |
|---|---|---|
| Washington | Gross misdemeanor — and the person who helps commits it too | Washington names the ways out that people actually try and makes each of them the offense: disconnecting the device, using a filter, asking someone else to blow. Whoever does the blowing is separately guilty of a gross misdemeanor. Any sentence runs consecutively with the sentence for the drunk driving case itself, not alongside it. Washington State Legislature, RCW 46.20.750 · RCW 46.20.750 · checked 2026-08-30 |
| North Carolina | Class 1 misdemeanor, counted per attempt | North Carolina adds one word that changes the arithmetic: each act of tampering, circumvention or attempted circumvention is a separate violation. A month of workarounds is not one charge. North Carolina General Assembly, G.S. 20-17.8A · N.C.G.S. § 20-17.8A · checked 2026-08-30 |
| Kansas | Class A misdemeanor, and the clock restarts | Kansas adds 90 days to the restriction on a first conviction. On a second, it does not add anything — it restarts the original restriction period from the beginning. Driving a vehicle without a device restarts it too. Kansas Statutes, K.S.A. 8-1017 · K.S.A. 8-1017 · checked 2026-08-30 |
| Missouri | Class A misdemeanor | Missouri writes the offense from both ends: asking someone to blow for you, and being the person who blows. Both are the same class A misdemeanor. Missouri Revisor of Statutes, RSMo 577.612 · RSMo § 577.612 · checked 2026-08-30 |
| Vermont | A civil penalty for the friend | Vermont is the mildest of these on the helper and still not free: knowingly tampering on behalf of another person, or otherwise helping them circumvent, carries a civil penalty of up to $500. Vermont Statutes, 23 V.S.A. § 1213 · 23 V.S.A. § 1213(k) · checked 2026-08-30 |
We do not publish methods, and this page never will. The device sits between a drink and a car, and the people it protects are not party to the argument.
Violation questions
What happens if you get a violation on an interlock?
It depends on how your state counts. Colorado does not act on one event — it acts when readings of 0.025 or more appear in three of any twelve consecutive months, and then extends the requirement by up to a year. The District of Columbia is stricter and more mechanical: 60 extra days for a first violation, 90 for a second, 120 for each after that. New Hampshire routes every alleged violation to a hearing first.
I failed an interlock test then passed. Is that a violation?
Often not, and the District of Columbia writes the rule out: an attempt above 0.020 is not counted as a violation if a reading within the next five minutes comes back below 0.020. Colorado excludes false results caused by mouth alcohol from what it counts, and Vermont lets the Commissioner disregard a reading where the pattern of tests shows it was not drinking. Wait a few minutes, rinse with water, blow again.
Will I go to jail for failing an interlock test?
A failed breath test is handled administratively — extensions, suspensions, hearings. What carries criminal exposure is circumventing the device, and that is a separate offense: a gross misdemeanor in Washington, a Class 1 misdemeanor in North Carolina, a Class A misdemeanor in Kansas and Missouri. If you are on probation, a positive reading can also be reported as a probation violation, which is a different proceeding with its own consequences.
What is an interlock camera violation?
Most programs photograph whoever provides the sample. New Hampshire defines tampering to include any act that stops the camera taking a clear photograph identifying the driver — so a hand, a sticker or a deliberately bad angle is not a way around the record, it is the violation itself.
Can someone else blow into my interlock?
No, and in several states both people commit an offense. Washington makes it a gross misdemeanor to ask someone to blow for you and a separate gross misdemeanor for them to do it. Missouri writes the offense from both ends as well. Vermont fines the helper up to $500. The camera is there precisely to answer this question after the fact.
What happens if you miss a rolling retest?
It is recorded as a violation in its own right, not as a technicality. New Hampshire requires the first retest 5 to 15 minutes after starting and then every 15 to 45 minutes. Vermont goes further and requires you to pull over and switch the engine off as soon as practicable after failing one — not doing so is a criminal offense there.
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