Any Victorian driver who blows over the blood-alcohol limit will be forced to install an interlock to their car, under under tough new road safety laws.

Roads minister Luke Donnellan said the new policy was tough, "but if your mother, your sister does not come home, that's pretty tough as well".

An alcohol interlock is a device hard-wired to a car's ignition. The car can only be started by blowing into the interlock which checks the blood-alcohol content of a user's breath. New alcohol interlocks also incorporate a camera to check the person blowing into the device is really the person behind the wheel.

Interlocks are expensive, and previously had only been used for drivers who were significantly over the blood-alcohol limit.