This paper outlines and explains the potential role of passive alcohol sensors to improve the enforcement of present drunk driving laws in the United States. A passive alcohol sensor is an electronic sensing device used to detect alcohol on a driver's breath. The legal framework created by the Fourth Amendment to the Constitution with which the police enforcement program must conform is also discussed. The passive alcohol sensor is a more effective and objective method of detecting alcohol on a driver's breath than the traditional question/answer interview. Another advantage of this device is that unlike the preliminary breath tester, the passive alcohol sensor is non-intrusive and would probably not be considered a “search” by the courts. Therefore, the PAS could be an effective law enforcement tool to help reduce alcohol-related fatalities in the United States.