Balance of probabilities

In a civil claim, the balance of probabilities is the requisite standard of proof by which a trier of fact (usually a magistrate or judge in civil proceedings) must determine the existence of contested facts. The balance of probabilities when a matter is judged as a whole is a reference to the likelihood of one party’s version of events being more probable to have occurred than not (TNT Management Pty Ltd v Brooks (1979) 23 ALR 345).
Evidence adduced by both parties must be analysed by the trier of fact is weighed up and a determination is made as to whether the party upon which bears the onus of proof (a Plaintiff in a civil proceeding) has proved its case.

Section 140 of the Evidence Act 1995 (NSW) (of which forms part of the Uniform Evidence Law in Australia) states that in NSW the standard of proof:

  1. In a civil proceeding, the court must find the case of a party proved if it is satisfied that the case has been proved on the balance of probabilities.
  2. Without limiting the matters that the court may take into account in deciding whether it is so satisfied, it is to take into account:
    • the nature of the cause of action or defence, and
    • the nature of the subject matter of the proceeding, and
    • the gravity of the matters alleged.

Section 140(2) is reference to the varying strength of evidence that is necessary to establish the existence of a fact on the balance of probabilities in cases that involve allegations of serious wrongdoing (such as fraud). The practicality of the balance of probabilities mandates that the standard shift so evidence and facts are judged accordingly (see Neat Holdings v Karajan Holdings Pty Ltd & Ors (1992) 110 ALR 449).
The balance of probabilities is not exclusive to civil proceedings. Pursuant to section 141(2) of the Evidence Act 1995 (NSW), in criminal proceedings, the balance of probabilities is the standard upon which a defendant must prove the existence of a fact in circumstances when such an onus exits.