Decided February 24, 1914.
Weeks was arrested while he was at work (I'm not really sure what for, this decision kinda starts in the middle of the story). After he arrest, some other cops went to his house. A neighbor showed them where the key was, and so they went in and searched it. They found some incriminating papers, and brought all this to the attention of a US marshal. The marshal returned to Weeks' house and searched it again, and found more incriminating paperwork.
Weeks objected to the seizure of his property and petitioned the court for its return. The court ordered that any seized property which wasn't going to be used as evidence must be returned to him, and some of his stuff was given back. At his trial, Weeks again objected to the seizure of his property, arguing that it was taken in violation of the 4th and 5th Amendments. The trial court declined to return the rest of the papers to him, and they were admitted as evidence. Weeks was convicted of using the mail to transport gambling materials.
He appealed. The Supreme Court observed that if evidence could be seized in violation of the 4th Amendment and admitted in trial, then there really wasn't much point to having a 4th Amendment. The court ruled that the evidence should have been returned to Weeks and not admitted at trial, and the exclusionary rule was born (although that phrase doesn't appear anywhere in the decision). The court only applied this reasoning to the actions taken by the marshal, declining to explore what remedies Weeks may have had against state officials (that sort of reasoning went away 50 years later with Mapp v. Ohio).