et al. Michigan Department of State Police v. Sitz

The ruling gave state authorities a powerful tool for curbing drunk driving, as it allowed police to stop all cars at checkpoints and look for drunken drivers. This stop is a "reasonable" seizure under the Fourth Amendment, since the checkpoints are an effective way to reduce drunk driving, reducing drunk driving is a legitimate state concern, and the sobriety checks are not intrusive on drivers.

In May of 1986, Michigan State Police set up a sobriety checkpoint along a stretch of Saginaw County highway in a publicized campaign to combat drunk driving. It was the state's first and only such action, and had been prompted by Michigan Governor James J. Blanchard, who had suggested adoption of the program a few months earlier in his State of the State address. Nationwide, alcohol-related fatalities topped 23,000 annually during the 1980s, though these figures were steadily declining as anti-drunk-driving campaigns and other deterrent programs, such as MADD (Mothers Against Drunk Driving), became more commonplace.

Sobriety checkpoints had been used in other states with mixed results. Opponents argued that the rate of arrest was insignificant compared to the inconvenience presented to motorists, not to mention the tax dollars used. Supporters of the program asserted that if a checkpoint found just one percent of a hundred drivers detained to be driving under the influence, that might yield at least one innocent life saved from a fatal collision. Checkpoint advocates also argued that the program's true effectiveness lay in deterring intoxicated people from getting behind the wheel of a car. Such programs had been challenged in other state courts, with varied outcomes: some judges had declared them unconstitutional on the basis that unreasonable search and seizure violated Fourth Amendment rights; other courts upheld them.