The ignition interlock is a great and effective tool to prevent drunk driving. The fuel cell is extremely sensitive and accurate for hydroxyl compounds and will prevent a drunk person from driving 100% of the time. The problem is just that it's being misused. When it began, the law required the interlock devices be "alcohol specific", meaning to only detect drinking liquor (the compound C2H6O). However, the truth is that fuel cell interlocks are alcohol specific.