McNamara v The King

McNamara appealed to the High Court of Australia against his conviction for murder. The central dispute concerned the admissibility of evidence obtained through a covert recording made by a police informant, which the appellant argued was obtained in contravention of his rights. The High Court was required to determine whether the admission of this evidence at trial was lawful, particularly in light of the circumstances under which it was obtained.

The primary legal issue before the High Court was whether the admission of the covertly recorded evidence was an error of law that necessitated quashing the conviction. This involved considering the application of the common law exclusionary rule, which generally permits the admission of relevant evidence even if obtained improperly, against any potential residual discretion to exclude such evidence in exceptional circumstances. The Court also had to consider the scope and application of the implied constitutional right to be tried according to law.

The High Court, by majority, held that the admission of the covertly recorded evidence was not an error of law. The majority reasoned that while the recording may have been obtained in circumstances that were not ideal, it did not fall within the narrow category of evidence that the common law requires to be excluded. They affirmed that the common law exclusionary rule is generally permissive, and that the implied constitutional right to be tried according to law does not operate to exclude relevant evidence simply because it was obtained improperly, unless its admission would fundamentally undermine the fairness of the trial process. The Court found that the admission of the evidence did not reach this threshold.