An ignition interlock is a breathalyzer installed into a car that will not allow the car to start until given a breath sample that has a lower Breath Alcohol Content(BAC) than the ignition interlock has programmed into it.

At random times after the engine has been started the ignition interlock will require another breath sample. If the breath sample isn't provided or the sample provided exceeds the ignition interlock's preset BAC level it will log the event, warn the driver and then start up a specific alarm system (e.g., lights flashing, horn honking, etc.) until the ignition is turned off.

Many countries have or are adding the ignition interlock as a penalty for drivers convicted of driving under the influence, especially repeat offenders.

External links

• Ontario Ministry of Transportation: Ignition Interlock
• FloridaIgnition Interlock Program
• MADD: Ignition Interlock - Issue Brief