A little more research on the subject turned this up. The U.S. Constitution seems to be the most eroded document in history...
"Michigan Department of State Police v. Sitz, 496 U.S. 444 (1990): This was the first major U.S. Supreme Court case on the issue of checkpoints conducted to promote highway safety. It upheld stops of vehicles at checkpoints without individualized suspicion, so long as the vehicles are stopped according to a neutral, articulable standard, e.g. every vehicle, every other vehicle, etc."
http://www.oyez.org/cases/1980-1989/1989/1989_88_1897