Rules of Evidence
For evidence to be admissible, it must bear a sufficient relationship to the actual event(s) that constitute the alleged breach of law. Evidence that is insufficiently related but which is nevertheless inflammatory may, if admitted, have the effect of swaying the jury or judge without having a really solid connection to the core material facts. Disallowing irrelevant evidence therefore helps to ensure a fair trial. It also prevents much time being wasted on hearing facts that will have no effect on the strict logic of the case.
The principle provision on relevance is Section 55. To phrase it clearly, sub-section 1 says that evidence is admissible if it will, directly, or indirectly, help to establish whether a fact in issue is true or false. A fact in issue is anything that must be established by either party to prove their case or debunk the other’s case.
Sub-section 2 specifies that evidence is not to be ruled irrelevant just because it goes to the credibility of a witness, the admissibility of other evidence, or a failure to adduce other evidence.
As an illustration of how relevance works, consider R v Buchanan. The defendant driver was charged with manslaughter in relation to a car collision. (These days the offence of culpable driving would apply). He admitted to drinking heavily that day. Witnesses testified that they saw him driving very fast 35 to 40 minutes prior to the accident. The evidence was admitted at trial, but an appeal was brought on the admissibility of evidence as to what happened that long before the accident.
The court ruled that the real issue was whether the accused was still driving with culpable negligence at the time of the accident. The fact of intoxication provided a connecting link between the Lewis’ evidence and the incident of the crash. If no alcohol had been involved then lacking a connecting link, the Lewis’ evidence would have been inadmissible as irrelevant.
Evidence that directly goes to the probability of an alleged fact being true is directly relevant. Evidence that is indirectly relevant goes to the reliability or credibility of other evidence or of a witness. This sort of evidence is admissible even though it says nothing about the facts in issue.
Under section 57 where relevance is not readily apparent and depends on some other fact to establish its relevance, the evidence can be admitted provisionally. Examples include documentary evidence where the document has to be authenticated later, or the characteristics of an object may be of interest, and admitted with an undertaking to adduce evidence later establishing that it was actually involved in the events in question.
Under section 58, a court may examine a document to determine its relevance. In effect it is admitted into evidence temporarily until the examination shows it is inadmissible.
 R v Buchanan  VR 9.
All statutory sections from unspecified Acts, are sections from a model Act of the Commonwealth Parliament as described on the first page of this chapter, and should be replicated as described in each of the related Acts of each State and Territory. (Jurisdiction to regulate the rules of evidence exists in the States and Territories and not in the Commonwealth).