Tenderella, an off-duty police officer, approached Capwell (D), who was standing outside Tenderella's house with a gas can, and asked him what he was doing there at 3 a.m. Tenderella patted D down for weapons after he noticed a bulge under D's coat. D swung the can and struck Tenderella. Tenderella attempted to place D under arrest. D kicked him in the arm and struck him again with the can. At trial, Tenderella testified that he felt pain when struck, and he neither sought medical care nor missed any work. D was convicted of assault in the fourth degree; an intentional causing of physical injury to another. 'Physical injury' was defined as physical impairment or substantial pain. D appealed; there was insufficient evidence to show that Tenderella suffered substantial pain or physical impairment.