Ignition Interlock

Where we stand: MADD is dedicated to supporting state legislation that expands the use of current alcohol ignition interlock technology so that interlocks are mandatory for all convicted drunk drivers in all 50 states. MADD works closely with state lawmakers to encourage passage of this lifesaving legislation.

The main reason people drive drunk today is because they can. Technology currently exists that has the potential to eliminate repeat drunk driving offenses – the alcohol ignition interlock. To realize a nation without drunk driving, we must substantially increase the use of ignition interlocks to include all convicted drunk driving offenders.

What Is an Alcohol Ignition Interlock?

• An alcohol ignition interlock is a small, sophisticated device – about the size of a cell phone – which is installed into the starting circuit of a vehicle.
• A driver must blow into the device and the vehicle will not start if the driver has measurable alcohol (set to a predetermined level) in their system.
• If the driver does not have alcohol above the measurable level in their system, the vehicle will start normally.
• Interlocks may be set for “running retests,” which require a driver to provide breath tests at regular intervals, preventing drivers from asking a sober friend to start the car.
• If a driver fails a running retest, the vehicle’s horn will honk and/or the lights will flash to alert law enforcement – the vehicle will not stop. The interlock does not have the ability to stop the vehicle once it is running for safety reasons.

Interlock Facts

• Alcohol ignition interlocks are proven to be an effective tool in the battle against drunk driving.
• Studies have shown ignition interlocks are an average of 64 percent effective in reducing repeat drunk driving offenses.^[1]
• Research shows that those convicted of drunk driving for the first time have driven drunk more than 87 times before their first arrest.^[2]
• Two-thirds of drunk driving offenders continue to drive even when their license is suspended.
• Only one out of eight convicted drunk drivers each year currently has an interlock on their vehicle.
• There are 1.4 million DUI/DWI arrests and about 1 million convictions made every year but only 135,000 vehicles with ignition interlocks nationwide.
• 65 percent of the public favors mandatory interlocks for first-time convicted offenders.^[3]
• 85 percent of the public favors mandatory interlocks for repeated convicted offenders.^[4]
• Offenders themselves believe interlocks are a fair and effective sanction:
  • 82 percent believe interlocks were very effective in preventing them from driving after drinking.
  • 68 percent believed interlocks were very successful in changing their drunk driving habits.^[5]
• Judicial and administrative enforcement is necessary to the success of interlock enforcement.
• Nearly 4,000 lives could be saved if ignition interlocks were installed on convicted offenders’ vehicles.^[6]