It’s become known as the “Peaches” case. In March 2008, District of Columbia police were called to a raucous party at a vacant house in DC.

Someone let the cops in. The officers thought they smelled marijuana, took note of a chaotic scene with beer bottles scattered about, and arrested all 21 partygoers on trespass charges.

More than one guest contended, however, that a mysterious woman named Peaches had given them permission to be there.

How did this case play out in court? And what can we learn from it about Fourth Amendment protections against unlawful searches and seizures?

At the police station, the charges were reduced from unlawful entry to disorderly conduct. Later they were dropped entirely.

Many of the partygoers – 16 of the 21 who were arrested – then sued the police for false arrest. They brought a civil rights lawsuit based on the Fourth Amendment, as well as related claims under District of Columbia law.

A federal judge found for the partygoers and awarded them hundreds of thousands of dollars. A federal appeals court affirmed this ruling.

But the U.S. Supreme Court reversed the ruling. Writing for the Court, Justice Clarence Thomas said that the barren condition of the house supported the police officers’ judgment that partygoers knew they were unjustifiably using a vacant house.

The Court not only found probable cause for the police to arrest the partygoers; the majority of the Court also said the officers had qualified immunity from being sued because they had reason to believe they did have probable cause.

Justices Sonia Sotomayor and Ruth Bader Ginsburg expressed concerns about the Court’s reasoning. Sotomayor said the Court should not have even considered the probable cause issue because the officers had qualified immunity. Ginsburg said the Court should look further in a future case on how a police officer’s reasons for arrest affect probable cause determinations.

The bottom line, however, was a win for the police. Though formally called District of Columbia vs. Wesby, it may long be known as the Peaches case.