Acts taken in self defence must be proportional to the threat posed, and to and difference in the power of the parties. This applies equally whether the danger comes in the form of a mere threat or a physical attack. In tort law the opportunity to act in self defence is more restrictive than in criminal law. Going back to Fontin v Katapodis, the defendant was criticised by the court for three things:
The throwing of a piece of glass was a reaction out of proportion to the initial attack, being the throwing of a T-square.
Standing his ground and retaliating when he had to opportunity to move away from the plaintiff and avoid further attack.
The victim of an attack therefore must think carefully when under attack. If there is a viable alternative to counter-attack then the alternative will be required by law. Of course it is possible that running away, attempting to subdue the attacker without risking injury, or calling for help will be pointless if the attacker is determined or out of control. In those circumstances the law will permit you to protect yourself by the most prudent and proportional manner available.
If a person’s involvement in a physical altercation is a result of their job, as is often the case for security guards and body guards, then there is a very good reason for not vacating the incident scene in that other persons or property still need protection. There is a contract requiring threats be reduced and/or eliminated. Any law of self defence conflicting with this would make every contract of service and any contract of employment concerning security guards or body guards void for illegality of terms. A law requiring the breach of very common contractual terms which operate clearly in the public interest would be of no merit. Therefore a person employed for protective purposes should not be required by a court to absent themselves from danger when duty demands otherwise. This, however, does not justify a person escalating a violent situation, needlessly placing themselves in harm’s way, or declining to take a non-violent means of solving a problem at hand.
ORDER FOR FULL TEXT.
 Fontin v Katapodis (1962) 108 CLR 177.
 Rozsa v Samuels  SASR 205.