An ignition interlock device is a breath-testing unit connected to a vehicle's ignition. The car will not start unless you blow below a set alcohol limit.
When one may be required
- After a DUI conviction in many states, including some first offenses.
- As a condition to restore driving privileges.
- For repeat offenders or high blood alcohol levels.
- As part of a plea or probation.
How it works
You blow into the device before starting the car. While driving, it may require random rolling retests. Results are recorded and reported to the supervising agency. Failed tests or tampering can extend the requirement or lead to penalties.
Costs and logistics
- Installation, monthly lease or monitoring fees and removal fees, paid by the driver, with hardship programs in some states.
- Regular calibration visits.
- The requirement can last months or years.
Practical tips
- Use an approved vendor from your state's list.
- Avoid foods, mouthwash and products with alcohol before testing.
- Follow retest instructions and keep a log.
- Tell anyone who drives your car how the device works.
- Do not tamper or have others blow for you.
Frequently asked questions
Can I drive other cars?
Usually you may not drive a vehicle without an interlock during the requirement.
Does the device record who blows?
Many include cameras.