Today's Supreme Court ruling on police searches reads like an episode of "Law & Order."

Police officers respond to a domestic disturbance call at the home of a couple that's had a rocky marriage. In front of the officers, the husband and wife trade accusations. She claims her husband's drug use is causing money problems and says actual "items of drug evidence" are in their home.

Hearing the suggestion that evidence might be inside, the police ask the husband if they can search the house. No way, he says. But the wife gives her consent and leads the officers to an upstairs bedroom, where they find a drinking straw with what looks like cocaine on it.

That very scene played out in reality five years ago at the home of a Georgia lawyer who was arrested and charged with drug possession.

Today, by a vote of 5-3, the U.S. Supreme Court said the search was illegal and that police who don't have a warrant cannot come into a house (or apartment, or college dorm room, for that matter) when one of the "cohabitants" objects.

Justice David Souter wrote the majority opinion, joined by Justices Stevens, Kennedy, Ginsburg and Breyer. The opinion says past search cases in this area all come down to what's commonly understood about the rights and responsibilities of people who live together. "A caller standing at the door of shared premises would have no confidence that one occupant's invitation was a sufficiently good reason to enter when a fellow tenant stood there saying, 'stay out.'" The same idea, Souter writes, is reflected in property law. When people live together, there's no superior and inferior, and each has an equal say in how the property is used.

Chief Justice Roberts, Scalia and Thomas dissented. Justice Samuel Alito took no part, because the case was argued before he joined the court.

In his first written dissent, Roberts says the ruling makes no sense and "protects a co-occupant who happens to be at the front door when the other occupant consents to the search." But he says the decision would not protect another occupant "napping or watching television in the next room" who doesn't happen to be at the front door to object. "If an individual shares information, papers, or places with another, he assumes the risk that the other person will in turn share access to that information or those papers or places with the government," Roberts writes. In this particular case, he says, the wife could just have easily walked upstairs, gotten the cocaine straw, and turned it over police. And, Roberts says, she could have consented "to police entry and search of what is, after all, her home, too."