Alias · Kimura system
Policeman's hold
Also known as Hammerlock — the canonical term used on this site.
Training background: Wrestling and law enforcement term — refers to the arm-behind-back control used for restraint; the hammerlock is the submission version
The hammerlock folds the opponent's arm behind their back, attacking the shoulder via internal rotation and extension. Applied from side control and back control when the arm is exposed.