An ignition interlock is a breathalyzer that prevents the vehicle from starting.
When the driver blows into the handset, an alcohol specific sensor analyzes the breath sample and calculates the Breath Alcohol Content (BrAC). The engine can only be started if the BrAC is below the designated limit.
The ignition interlock programs are for people who have received a DUI/DWI. It is required for drivers who want to keep their licenses. Program participants need to install Ignition Interlock Devices (IID) in any vehicle that they drive. To install an ignition interlock, participants of this program need to register with an approved ignition interlock service provider. Program participants will also be required to meet with their service providers on a regular basis. The steps and length of the program changes from state to state.