http://en.wikipedia.org/wiki/Fourth_Amendment_to_the_United_States_Constitution#Exceptions http://en.wikipedia.org/wiki/Fourth_Amendment_to_the_United_... Wher

http://en.wikipedia.org/wiki/Fourth_Amendment_to_the_United_States_Constitution#Exceptions http://en.wikipedia.org/wiki/Fourth_Amendment_to_the_United_... Where society's need is great and no other effective means of meeting the need is available, and intrusion on people's privacy is minimal, checkpoints toward that end may briefly detain motorists. In Michigan v. Sitz 496 U.S. 444 (1990), the Supreme Court allowed discretionless sobriety checkpoints.