• In court the plaintiff has the burden of establishing (proving) that the tort of negligence has been committed. They must prove the negligence caused their injuries on the 'balance of probabilities'. That means the court must be convinced that it is more likely than not that the defendant’s negligence caused the damage complained of.
• The defendant may choose to argue and bring evidence to establish that:
  • they did not owe a duty to the plaintiff;
  • there has been no breach of duty;
  • the defendant did everything reasonably possible to avoid harm; and
  • the defendant’s negligence did not cause harm to the plaintiff.
• Since the onus of proof lies on the plaintiff the defendant only needs to cast sufficient doubt on the plaintiff’s case. They do not need to prove that the negligent act did not happen. If the plaintiff cannot prove that on the balance of probabilities negligence has occurred then their case will fail.
• Challenging the plaintiff’s case is not the same as providing a defence to the plaintiff’s claim. If the defendant raises a defence then the onus (responsibility) shifts and the defendant has to  prove on the balance of probabilities that their version of events is more likely.
• There are two main defences available for tort of negligence.

A) Assumption of risk by plaintiff

• The first main defence is that of ‘volenti non fit injuria’ (assumption of risk). This means that the plaintiff took the risk upon himself or herself. They knew that something was inherently dangerous and voluntarily accepted that risk of their own accord. If a plaintiff takes the risk of injury on himself or herself then they cannot raise a tort of negligence and cannot recover any damages.
• To prove the defence the following elements must be established:
  • the plaintiff must have had actual knowledge of risk at the time of the incident; and
  • the plaintiff must have acted voluntarily and with full appreciation of the risks involved.
• It is very difficult to successfully establish this defence. For example courts usually take the view that in most circumstances the plaintiff never fully appreciates the risks. Some examples of cases where the defence has not been accepted by the court are:
  • a plaintiff who hired an ex-convict knowing that they had been previously jailed for violent assault was held not to have voluntarily accepted the risk of being shot by their ex-convict employee. This was established in the case of Monie v Commonwealth of Australia [2007] NSWCA 230; and
  • a plaintiff who knew the footpath might be slippery was found not to have fully appreciated the risk of falling. This was established in the case of Randwick City Council v Muzic [2006] NSWCA 66. It should be noted that slips and falls on sidewalks and in shopping centres are a very common category of tort claims and that there are many factors to be considered in order to prove liability.
• An example of where the defence may made out is where an employee consents to working in an environment where there are inherent which cannot be avoided by the employer exercising due care.

B) Contributory negligence

• Then defence of contributory negligence refers to the situation where the plaintiff contributed to the damage through their own negligence. To establish this defence the following requirements need to be proven by the defendant:
  • the plaintiff failed to observe a duty of care towards them self by not taking reasonable care for his or her own safety;
  • the plaintiff's own negligence (breach of the duty of care) was a cause of their harm;
  • the plaintiff's conduct caused or aggravated the damage; and
  • the damage that occurred was not too remote from the actions or omissions of the plaintiff.
• The defendant bears the onus of proof and must prove that the plaintiff breached the required standard of care for their own safety. When proving the breach of duty of care the test of reasonable foreseeability is used.
• In NSW section 5R of the Civil Liability Act 2002 (NSW) states that reasonableness is measured subjectively according to what the specific plaintiff knew of ought to have known at the time. If the plaintiff acted reasonably 'in the agony of the moment' then they may not be considered to have breached their duty of care.
• The actions of the plaintiff are weighed against the danger caused by the defendant. Although courts in Australia tend to take a lenient approach and prefer not to penalise the plaintiff too harshly for their contributory negligence some states and territories in Australia have laws that enable courts to reduce damages by 100%. This is possible in NSW although rarely applied.