Sir Robert Peel in the context of Double first

The use of force, in the context of law enforcement, may be defined as "the amount of effort required by police to compel compliance by an unwilling subject." Multiple definitions exist according to context and purpose. In practical terms, use of force amounts to any combination of threatened or actual force used for a lawful purpose, e.g. to effect arrest; defend oneself or another person; or to interrupt a crime in progress or prevent an imminent crime. Depending on the jurisdiction, legal rights of this nature might be recognized to varying degrees for both police officers and non-sworn individuals; and may be accessible regardless of citizenship. Canada's Criminal Code, for example, provides in section 494 for arrest in certain circumstances by "any one."

Use of force doctrines can be employed by law enforcement officers and military personnel, who are on guard duty. The aim of such doctrines is to balance the needs of security with ethical concerns for the rights and well-being of intruders or suspects. Injuries to civilians tend to focus attention on self-defense as a justification and in the event of death, the notion of justifiable homicide. Sir Robert Peel has stated: “Police use physical force to the extent necessary to secure observance of the law or to restore order only when the exercise of persuasion, advice and warning is found to be insufficient.”