Interlock Requirements
Ignition Interlock in Texas
An interlock is not only a sentence. In many DWI cases it attaches as a condition of release, months before any finding of guilt.
There is also a cost relief provision almost nobody writes about, and it applies far more narrowly than it is usually described.
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When an interlock is mandatory
Texas ignition interlock requirements
| Stage | When it is required |
|---|---|
| On bond, article 17.441 | A charged subsequent DWI or BWI offense, and any charge of child passenger DWI, intoxication assault or intoxication manslaughter. Installed within 30 days unless the court finds it not in the best interest of justice. |
| On probation, article 42A.408 | Where the alcohol concentration was 0.15 or higher, for a repeat offender, or for a driver under 21. |
| On deferred adjudication | Mandatory for DWI or BWI deferred unless waived after an evaluation. |
| Second offense within 5 years, section 49.09(h) | On every vehicle owned or operated, until the first anniversary of the end of the license suspension. |
Where an interlock is ordered as a probation condition, it must run for at least half the supervision period. An employer vehicle exception exists in narrow circumstances under article 42A.408(h).
What the device records
When an ignition interlock is ordered under Code of Criminal Procedure article 42A.408, the provider report can contain more than a passed or failed breath sample. Depending on the equipment and order, it may include timestamps, missed or aborted tests, lockouts, rolling retests, service visits, and images. A reported event should be compared with the device serial number, service and calibration history, driver identity, timestamp, repair or power records, and provider notes. The event log is evidence to evaluate, not a substitute for identifying who used the vehicle and whether the device was operating properly.
The indigency relief, scoped correctly
Article 42A.408(e-1) provides real cost relief: a waiver of the installation charge and a fifty percent reduction in the monthly monitoring fee. It is worth a substantial amount over the life of an order.
But it is much narrower than it is usually described, and getting this wrong sets up a false expectation. It is available only where a judge grants deferred adjudication for a section 49.04 or 49.06 offense. Not on conviction. Not on ordinary probation.
A probationer whose case ended in a conviction gets something much more limited under article 42A.408(f): a reasonable payment schedule. That is not a reduction, it is time to pay.
The relief also does not cover alcohol detection device fees, which are billed separately. Anyone planning around this needs the distinction clearly, because the gap between a fee waiver and a payment schedule is the difference between affordable and not.
Where an interlock works in your favor
Two provisions turn the device from a pure burden into something worth considering deliberately.
On an occupational license, section 521.248(d) exempts interlock restricted drivers from all time, route and purpose limits. An ordinary occupational license permits four hours of driving a day on defined routes. With an interlock, none of those limits apply.
On sealing, a six month interlock condition cuts the waiting period from five years to two on a conviction with probation, and from five to three without one. That is years of difference produced by a condition many people resist.
Worth raising early
Both of those effects are decided at points in the case where the interlock is being discussed anyway.
Treating it purely as something to avoid can cost more than accepting it deliberately.
Related pages
Ignition interlock questions
Do I have to fit one before I am convicted?
Often yes. For a charged subsequent offense, or any charge involving a child passenger, intoxication assault or intoxication manslaughter, it is a mandatory bond condition under article 17.441, installed within thirty days.
I cannot afford it. Is there help?
There is, but narrowly. The installation waiver and fifty percent monitoring reduction under article 42A.408(e-1) apply only where a judge grants deferred adjudication for a section 49.04 or 49.06 offense. On a conviction, article 42A.408(f) offers only a reasonable payment schedule.
Does it go on every vehicle I own?
On a second offense within five years, yes. Section 49.09(h) requires one on every vehicle owned or operated until a year after the suspension ends.
Is there any advantage to having one?
Two real ones. It removes all time and route limits on an occupational license, and a six month condition substantially shortens the waiting period before a record can be sealed.