This case, otherwise known as the Peaches’ House Party Case, deals with probable cause and qualified immunity of police officers. Justice Thomas wrote the opinion for a unanimous court overturning judgments of almost $1,000,000 awarded to partygoers for what the lower court found to be their unlawful arrest. Turns out, the plaintiffs had entered an unoccupied house and, well, had a party. When neighbors complained and the police showed up, some of the partygoers were arrested.
The case itself:
From The Volokh Conspiracy on Reason.com:
Imagining a World Without Qualified Immunity, Part I