Justification: Self-Defense - Unlawful Threat

Force in self-defense may only be used against a threat of unlawful force. Conduct that satisfies the definition of a criminal offense or tort is unlawful. But if such conduct is justified it is lawful; if the conduct is only excused it is unlawful. The definition of unlawful force in MPC section 3.11(1) is essentially the same as the common law except for also including unlawful confinement even if it does not involve any physical force.

Self-defense force cannot be justified in self-defense then against a police officer using lawful force to make a lawful arrest. If the police officer uses excessive and thus unlawful force, nondeadly self-defense force against it is justified. At common law, there was generally a right to resist an illegal arrest due to lack of probable cause, absence of warrant, or an improperly issued warrant. However, some states have now eliminated the right to resist such technically illegal arrests (e.g., Cal. Pen. Code 834a (1985)). The MPC similarly disallows self-defense against technically illegal arrests but does allow self-defense against excessive force arrests (section 3.04(2)(a)(i)). The trend toward eliminating the right to resist technically illegal arrests may be due to the amelioration of the harsh consequences following an arrest and the increased seriousness of resisting armed officers.