Motor vehicle ignition interlocks : in-vehicle devices that monitor alcohol levels of motor vehicle operators.

Ignition interlock units are in- vehicle alcohol sensing devices that compare the blood alcohol content of a vehicle operator with a preset limit. Legislation permitting the installation of ignition interlock devices on vehicles has only recently been introduced in some states of the US. The first such law was enacted in California in 1986. A number of legal and economic issues that must be considered if an ignition interlock program is initiated, are discussed.