A little after 2:00 a.m. on the first day of 2009, San Francisco Bay Area Rapid Transit (BART) Officer Johannes Mehserle arrived at the Fruitvale BART station after receiving reports of a fight on a train. On arrival, he was directed by another officer to arrest Oscar Grant, who, along with other fight suspects, was sitting on the ground next to the wall of the station. As Mehserle, who was joined by other officers, prepared to arrest Grant, Grant began to stand up, and Mehserle forced him to the ground face first. Another officer stood over Grant and uttered, “Bitch-ass n-.” As Mehserle attempted to handcuff Grant, some eyewitnesses testified that Grant resisted by keeping his hands under his torso. Although Grant was lying face down and was physically restrained by another police officer at the time of his alleged resistance, Mehserle removed his department-issued handgun from its holster and shot Grant in the back from point-blank range. Grant died later that morning.

At trial, the jury convicted Mehserle of involuntary manslaughter, but acquitted him of more serious homicide charges that would have treated the killing as intentional. The involuntary manslaughter conviction indicates that the jury likely believed two key pieces of Mehserle's testimony: first, that he thought Grant was reaching for a gun, and second, that he mistook his own gun (which was on the right side of his body and weighed twice as much) for a Tazer (on the left side of his body). How could an officer possibly perceive a mostly compliant, restrained man as a gun-toting threat?