CBS News Correspondent Jim Stewart reports that the courts have lately broadly expanded the power of police to stop and search, including authority to detain someone simply because they fled when police approached and the power to seize property if it was once thought to be used in a crime.
The Court's unanimous decision upheld a Florida Supreme Court ruling that had thrown out the conviction of a man identified in court papers only as "J.L."
The justices said Miami police acted unlawfully five years ago, when they searched and arrested a juvenile who was carrying a gun.
They had received an anonymous tip saying that three black youths were standing in front of a pawnshop, and that the one in a plaid shirt was carrying a concealed gun.
"The question is whether an anonymous tip ... is, without more, sufficient to justify a police officer's stop and frisk of that person," Justice Ruth Bader Ginsburg wrote for the court. "We hold that it is not."
"Unlike a tip from a known informant whose reputation can be assessed and who can be held responsible if her allegations turn out to be fabricated, an anonymous tip alone seldom demonstrates the informant's basis of knowledge or veracity.''
Any resulting search violates that person's Fourth Amendment right against unreasonable police searches and seizures, the court said. The gun seized from J.L. therefore should not have been used as evidence against him, it said.
The nation's highest court 32 years ago ruled that police can stop and frisk someone without a court warrant if they reasonably believe the person has committed or is about to commit a crime. Tuesday's decision does not affect that ruling.
It states, however, that an anonymous tip most often cannot be the basis of a reasonable belief of wrongdoing.
But Ginsburg said the court was stopping short of saying whether anonymous tips can spark lawful police searches when "the danger alleged ... might be so great as to justify a search even without a showing of reliability.''
For example, she said, a report of a person carrying a bomb would not necessarily have to "bear the indicia of reliability we demand for a report of a person carrying a firearm before police can constitutionally conduct a frisk."
Police also might get more leeway "where the reasonable expectation of Fourth Amendment privacy is diminished, such as airports and schools,'' Ginsburg said.
Still, defense lawyers said the case could set some much needed boundaries.
"If you look at the fundamental relationship between people and police, then you need to say that police aren't going to be stopping people without any basis at all," Harvey Sepler, an Assistant Pblic Defender in Miami.
However, police said not acting on even anonymous tips can make a cop's job even more dangerous.
Stephen McSpadden, general counsel for the National Association of Police Organzations, said "I think what most people don't understand is how quickly a gun can come out and can be fired. You're talking about one or two seconds."
According to Cornell University's Supreme Court website, the Miami trial court granted J.L.'s motion to suppress the gun as evidence, but the intermediate appellate court reversed that decision. The Supreme Court of Florida quashed the appellate court ruling.