Chowdury v The Queen; McMillan v The Queen

These applications for special leave to appeal concerned the joinder of charges and the admissibility of evidence in criminal trials. The applicants, Chowdury and McMillan, sought to appeal decisions from lower courts. The High Court of Australia heard both applications together.

The primary legal issue before the Court was whether the trial judges erred in refusing to order separate trials for the applicants. This refusal was argued to have led to the admission of evidence that was not properly admissible against each applicant, particularly due to the joinder of conspiracy charges with other offences. The applicants contended that the prejudicial effect of such joinder, especially in cases involving a head conspiracy and multiple subconspiracies, was exacerbated, leading to a risk of injustice.

The applicants argued that courts have historically been reluctant to join conspiracy charges with substantive offences due to the potential for prejudice arising from the admission of evidence. They submitted that this prejudice is amplified when a head conspiracy is alleged alongside numerous subconspiracies, and that separate trials should have been ordered where the evidence admissible against one alleged conspirator differed significantly from that admissible against another. The applicants relied on cases such as *Darby*, *Guimond v Reg*, and *Director of Public Prosecutions v Shannon* to support their submission that the failure to order separate trials was a fundamental error.