R v Mohammadi

The appeal concerned Morteza Mohammadi, who had been convicted by a jury of aggravated recklessly causing serious harm and threatening a person involved in a criminal investigation. The appellant alleged that the trial judge's conduct during the trial, including interventions during the evidence of an alibi witness and the adequacy of directions to the jury regarding the alibi defence, resulted in an unfair trial. The appeal was heard by the Full Court of the Supreme Court of South Australia, comprising Gray, Sulan, and David JJ.

The central legal issues before the Full Court were whether the trial judge's interventions in the questioning of witnesses amounted to material interference with the conduct of the trial, thereby giving rise to an unfair trial. Additionally, the court considered whether the judge's directions to the jury concerning the alibi defence were sufficient, particularly regarding the prosecution's onus of proof even if the alibi was rejected. The court also had to determine if any errors in the summing up, either individually or collectively, created a risk of a miscarriage of justice.

The Full Court, in allowing the appeal, found that the trial judge had not adequately directed the jury on the alibi defence, failing to instruct them that the prosecution retained the burden of proof even if the alibi evidence was disbelieved. Furthermore, the judge's interventions during the testimony of the alibi witness were perceived as indicating a view that the evidence was not credible. A majority of the court, including David J, concluded that this combination of factors led to an unfair trial concerning the charge of aggravated recklessly causing serious harm, and this unfairness extended to the charge of threatening a person involved in a criminal investigation. Gray and Sulan JJ agreed that the judge's interventions created a real risk of a miscarriage of justice, which was compounded by other errors.

Consequently, the Full Court allowed the appeal, set aside the verdicts of guilty, and remitted the matter for a retrial.