1.Reasonable belief of an imminent threat of receiving great bodily harm
i.When the threat expires so does the defense
ii.Reasonableness depends on each case’s own facts: size, age, strength of parties, their reputations for violence, who is aggressor, degree of physical harm reasonably feared, and presence/absence of weapons
2.Fear must be both real and reasonable Courvoisier v. Raymond.
The court found that C.’s act was justified because he believed that R. was a rioter and had made an innocent mistake. (not excessive force
3.May not use more force than reasonably necessary
4.Reasonable mistake allowed – accidental/inadvertent/involuntary
5.Some jurisdictions require retreat if it can be made safely