The police suspected that Oshan Cook had just dropped off some MDMA with a known dealer because his backpack looked lighter when he left the dealer's home than it did when he entered. When Mr. Cook went back to the dealer's home, carrying the same backpack, six officers arrested him at gunpoint, ordering him to the ground.
When Mr. Cook dropped to the ground, three of the six officers handcuffed him, and he was face down on the sidewalk, with three officers on top of him, and with his hands handcuffed behind his back. At which point one of the officers grabbed Cook's backpack, which Cook had dropped to the side when he was ordered to the ground, and searched it for twenty or thirty seconds.
The Ninth Circuit, in an opinion by Judge Nguyen, holds that this is okay. Because even though Mr. Cook had a small build, had three officers on top of him (and three more nearby), and was planted face-down on the sidewalk with his hands tied behind his back with handcuffs, it was reasonable to conclude that this face-down, handcuffed, dominated individual might perhaps break free and reach for the backpack. Hence the officers could reasonably search the backpack, even without a warrant, to make sure there were no guns in the backpack. Lest the prone, handcuffed, tiny Mr. Cook break out of his metal restraints, throw off the three officers on top of him, avoid the other three nearby, zip open the backpack, grab the (non-existent) guns therein, and shoot the officers dead.
So holds the Ninth Circuit.