The recent case of Beets v. County of Los Angeles arose after a deputy sheriff shot and killed a man in connection with a car theft and chase. The deputy claimed that he had to shoot the victim, Glenn Patrick Rose, because Rose was backing up the stolen car towards the deputy and he feared for his life.
Rose was with his girlfriend at the time, who was ultimately convicted of various crimes including assault on a peace officer under an "aiding and abetting" theory.
The Ninth Circuit decided that the police brutality Section 1983 case was barred by a doctrine known as Heck preclusion because a successful excessive force lawsuit would call into question the validity of the girlfriend's conviction as an accomplice. The Heck preclusion doctrine was established in the U.S. Supreme Court case Heck v. Humphry.
The Beets case left open the possibility that a plaintiff can proceed with a police brutality Section 1983 case under the theory set forth in Smith v. City of Hemet, where the alleged excessive force is outside the "temporal scope" of the conduct at issue in the underlying conviction.