By Ryan Botha on Monday, September 8, 2014 at 12:59amA person acts in private, and his/her act is therefore lawful, if he/she uses force to repel an UNLAWFUL attack which has commenced, or is imminent, that meaning the attack is clearly on the point of being executed, upon him/her or someone else’s life, bodily integrity, property or other interest which deserves to be protected, provided the defensive act is necessary to protect the interest threatened, is directed at the attacker, and is reasonably proportionate to the attack. A person can’t act in private defence against lawful conduct. Eg. resisting a police officer performing his duties lawfully, however they exceed the limits of their authority they may be resisted. Private defence against private defence is not possible except where the person exceeds the limits of private defence because then it has become unlawful. X may not attack Y merely because he expects Y to attack him at some time in the future, he may only do so if there is an attack or immediate threat of an attack by Y against him. In this case it is not necessary for him to wait for Y’s first blow, he may defend himself by attacking Y, with the precise object of averting that first blow. Private defence is not a means of exercising revenge or punishment, for this reason X acts unlawfully if he attacks Y when Y’s attack on him is already finished.