US v. Mowatt: Mowatt was at his apartment when police came and knocked on the door. The police were sent there after receiving complaints about loud music and the odor of marijuana. After they knocked, the officers heard someone moving around inside. The music was turned down and they could hear the sound of an aerosol being sprayed. Mowatt talked the officers, but refused to open the door. After being reported ordered to do so, Mowatt cracked the door, but refused to let the officers inside and asked if they had a warrant. Officers were concerned that Mowatt might have a weapon in his hand, as it was shielded from view. They then forced their way into the apartment and wrestled Mowatt to the floor. He wasn't holding anything in his hand. A quick check of the apartment uncovered a gun. By that time, Mowatt struggled with the officer(s) restraining him, which ended when he was thrown against the refrigerator, which conveniently opened. Inside, officers saw several hundred pink pills. They were later seized (pursuant to a search warrant) and determined to be ecstasy. The search also uncovered more guns, body armor, and $20,000 in cash.
After being indicted for drug and firearms offenses, Mowatt moved to suppress the evidence against him, arguing that the officers engaged in an unlawful warrantless search when they barged into his home. The district court denied the motion, holding that the officers had probable cause to arrest Mowatt for marijuana possession and that a warrant wasn't required because they arrived at the apartment to "resolve a noise complaint" rather than search for drugs. Mowatt went to trial, was convicted on all counts, and was sentenced to 197 months in prison.
On appeal, the Fourth Circuit unanimously reversed. First, the court rejected the Government's argument that forcing Mowatt to open his door and thus being able to see inside was not a "search" within the meaning of the Fourth Amendment. Second, the court held that even if the officers had probable cause when the door was opened, they lacked a warrant and there were no exigent circumstances to justify proceeding without one. Third, the court held that the search warrant eventually obtained (after the forced entry, struggle with Mowatt, etc.) was tainted by the illegal entry. Mowatt's convictions were reversed and his case returned to the district court for further proceedings.