Data came from 2 sources: interviews and participant observations in a northeastern city during 10 months in 1976-77 and an analysis of 459 police shootings in Philadelphia between 1970 and 1978. Accounts of these shootings had been gathered from police, witnesses, and surviving victims by the Philadelphia Public Interest Law Center. The police departments had guidelines for use of weapons, and every shooting was subject to a formal review. However, police regard the review process as generally friendly and the legal standards as vague enough to permit the interpretation of nearly all shootings as justifiable police homicide. The police subculture has special understandings about using firearms against citizens. Violations of these understandings are justified on the grounds that violent treatment is permissible for certain types of persons and under certain kinds of circumstances. Three case accounts show how responsibility for the shooting is deflected to the conduct of the person shot or to special circumstances at the scene. The ultimate excuse is that the weapon discharged accidentally. Thus, in the context of cultural and legal prohibitions against taking life, police are able to assemble a sense of justification for their use of deadly force. It is doubtful that formal restrictions on the use of firearms will be effective, because such control efforts operate against a background of subcultural beliefs and justifications that are supported both organizationally and politically. Thirty-four references and one case citation are supplied.