The U.S. Supreme Court ruled Tuesday that police may set up roadblocks to collect tips about crimes, rejecting concerns that authorities might use the checkpoints to fish for unrelated suspicious activity.
The 6 to 3 decision, in a case in which Illinois authorities were supported by Louisiana, allows officers to block traffic and ask motorists for help in solving crimes.
Critics have complained that authorities might misuse the power, disguising dragnets as "informational checkpoints.''
Roadblocks are used for a variety of investigations. For example, in 2002, police used them to try to produce leads in the Elizabeth Smart kidnapping in Utah and the sniper shootings in the Washington, D.C. area. But the Supreme Court has limited their use.
Although the justices have allowed random sobriety checkpoints to detect drunken drivers and border roadblocks to intercept illegal immigrants, they ruled in 2000 that roadblocks intended for drug searches are an unreasonable invasion of privacy under the Constitution.