Self-defence (legitimate defence)

Self-defence justifies acts committed out of the necessity to repel an unjust attack that is occurring, or whose occurrence or repetition is certain. The attack may target any defensible right of the defender or of a third person.

Its conditions are twofold. As to the attack: it must be unjust and ongoing or imminent at the moment of defence; acting against an attack already over is retaliation, not defence. As to the defence: it must be proportionate to what repelling the attack requires, balancing the means used and the harm inflicted against the gravity of the attack.

Where the conditions are fully met, the defender is acquitted and no civil liability arises. Exceeding the limit through excitement, fear or panic attracts no punishment, while conscious excess leads to a reduced sentence. Defensive acts against attacks in homes and workplaces are where proportionality is most intensely contested in practice.