Cesan v The Queen; Rivadavia v The Queen

The High Court of Australia considered appeals by Cesan and Rivadavia against their convictions for conspiracy to import a commercial quantity of heroin. The appellants were convicted in the District Court of New South Wales, and their appeals to the Court of Criminal Appeal of New South Wales were dismissed. The central dispute revolved around the admissibility of certain evidence, specifically recordings of conversations made by a police informant.

The primary legal issue before the High Court was whether the recordings of conversations between the informant and the appellants, made without the appellants' knowledge or consent, were admissible in evidence. This question engaged the principles of the common law regarding the admissibility of illegally or improperly obtained evidence, and whether the discretion to exclude such evidence had been correctly exercised by the trial judge. A related issue concerned the proper application of the rule against hearsay in relation to statements made by co-conspirators.

The High Court held that the recordings were admissible. Gleeson CJ and Heydon J, in a joint judgment, reasoned that while the recordings were obtained in circumstances that might be considered improper, their probative value in proving the conspiracy was so high that the discretion to exclude them was not enlivened. They emphasised that the common law does not automatically exclude illegally obtained evidence, but rather requires a balancing of the evidence's probative value against its prejudicial effect and the impropriety of its acquisition. The Court found that the trial judge had correctly exercised this discretion. The appeals were dismissed.