Considering the centrality of the contested criminal trial in the popular imagination, there is a surprising lack of academic research into how contested trials operate. By design, alternative narratives are constructed and presented to the court to enable it to assess the factual and legal culpability of the accused. The rules of engagement are strict. Evidence that juries may find of relevance may sometimes be withheld – for example, evidence of previous bad character relating to an accused, or evidence of a complainant's sexual history in a rape case. This suggests that juries may attach disproportionate weight to evidence, jeopardizing the fairness of the trial. Issues also surround the use of expert witnesses. The presentation of complex evidence can lead to misunderstanding on the part of lay people and can also mask the fact that there can be scientific disagreement over the interpretation of evidence.

It is perhaps a common public perception that criminal trials will turn on questions of law. Legal practitioners spend approximately four years studying the law prior to qualification. In practice, however, few criminal cases are primarily about questions of law. In the overwhelming majority of criminal trials it is the facts that are disputed and in issue. The court will have to decide whether the necessary facts have been proved to a sufficient standard to meet the legal elements of the offence charged. As Susan Blake points out:

Adversarial justice

As its name suggests, adversarial justice rests on the idea that the truth will emerge from two competing narratives of the criminal event. The state presents its case before a neutral finder of fact who has to determine, beyond reasonable doubt, whether the case against the defendant is made out. The defendant has the opportunity of contesting the prosecution case, of disputing the evidence, of questioning the witnesses and of raising potential defences.