Which legal principle allows for the defense of others using physical force?

The legal principle allowing for the defense of others using physical force is grounded in the concept of a reasonable belief of threat. This principle asserts that an individual may justifiably use physical force to protect another person if they believe that person is facing an imminent threat of bodily harm or unlawful aggression. The belief must be reasonable, meaning that a typical person in the same situation would perceive a similar threat.

In the context of protecting others, the defender must assess the situation and determine if the threat is immediate and serious enough to warrant intervention through force. This principle is crucial in legal systems to ensure that individuals can protect vulnerable parties from harm while also establishing boundaries to prevent excessive or unjustified use of force.