A 911 operator received a call from a crying 12-year-old girl reporting that she, her mother, and her 15-year-old sister had shut themselves into a room at their home because her mother’s boyfriend, P, was trying to hurt them and had a chainsaw. The girl told the operator that Cortesluna was “‘always drinking,’” had “‘anger issues,’” was “‘really mad,’” and was using the chainsaw to “‘break something in the house.’” D heard the broadcast and responded to the scene along with four other officers. P heard the broadcast and responded to the scene along with four other officers. The officers spent several minutes observing the home and reported seeing through a window a man matching P’s description. One officer asked whether the girl and her family could exit the house. The family confirmed they “‘were unable to get out’” and confirmed that the 911 operator had “‘heard sawing in the background’” and thought that P might be trying to saw down the door. D knocked on the door and stated loudly, “‘police department, come to the front door, Union City police, come to the front door.’” When D ordered P to “‘drop it,’” P dropped the “weapon,” later identified as a metal tool. D then commanded, “‘come out, put your hands up, walk out towards me.’” P put his hands up and D told him to “‘keep coming.’” P was told to get on his knees and did so. Another officer then saw a knife sticking out from the front left pocket of P’s pants and shouted, “‘he has a knife in his left pocket, knife in his pocket,’” and directed P, “‘don’t put your hands down,’” “‘hands up.’” P turned his head toward the instructing officer but then lowered his head and his hands in contravention of the officer’s orders. Another officer twice shot P with a beanbag round from his shotgun, once in the lower stomach and once in the left hip. After the second shot, P raised his hands over his head. The officers shouted for him to “‘get down,’” which he did. Another officer stated, “‘left pocket, he’s got a knife.’” D then straddled P. He placed his right foot on the ground next to P’s right side with his right leg bent at the knee. He placed his left knee on the left side of Cortesluna’s back, near where P had a knife in his pocket. He raised both of P’s arms up behind his back. D was in this position for no more than eight seconds before standing up while continuing to hold P’s arms. Another officer, who had just removed the knife from P’s pocket and tossed it away, came and handcuffed P’s hands behind his back. D lifted P up and moved him away from the door. P sued under 42 U. S. C. §1983, claiming that D used excessive force in violation of the Fourth Amendment. The District Court granted summary judgment to D, but the Court of Appeals reversed. The Court of Appeals held that “D is not entitled to qualified immunity because existing precedent put him on notice that his conduct constituted excessive force.” The Court of Appeals relied solely on LaLonde v. County of Riverside. “Both LaLonde and this case involve suspects who were lying face-down on the ground and were not resisting either physically or verbally, on whose back the defendant officer leaned with a knee, causing allegedly significant injury.” The Supreme Court granted certiorari.