CNN notes that since 1993, Pennsylvania and all other states in America put laws in place to install ignition interlock systems in the cars of some drivers who had been caught driving drunk. Before starting the car, drivers were forced to test their blood alcohol content. If the device detected alcohol, then they would not be able to start the car.

Some states have mandatory laws, while others have partial laws. States that have mandatory laws require all persons convicted of a DUI to install a breathalyzer in the car. States that use partial laws, may require only a subset of convicted drunk drivers to use breathalyzers. Mandatory laws have led to a 7% reduction in fatal crashes involving drunk drivers.

Because of this initial success, states with partial laws are now considering mandatory laws. According to ABC news, at least 32 states and Washington D.C. require ignition locks even for first-offenders. Some people believe this may be far more effective than suspending a driver’s license. People might drive on a suspended license anyway, but if the car will not start, they may be more likely to stay off the road.

Note, however, that ignition locks do not present a perfect solution. Those who are forced to use them often complain about the cost of installation and maintenance. Installation costs up to $150 and maintenance may cost up to $80 per month.

These costs are typically paid for by the driver. Coupled with the likelihood of higher insurance premiums due to the drunk driving conviction, the cost of operating a vehicle becomes much higher for these drivers. The hope is that this may act as a deterrent to encourage people to drink responsibly and drive sober.