R v Cox; Ex parte Smith

The prosecutor, Bruce Malcolm Smith, a former Private in the Australian Defence Forces, sought a writ of prohibition against a general court-martial. Smith had been convicted of absence without leave and sentenced to detention and discharge from the forces. While serving his detention, he was charged with joining in a mutiny in His Majesty's Forces, an offence under section 7(3) of the Army Act (Imp.). The other individuals alleged to have participated in the mutiny were also former soldiers serving detention sentences and had been discharged. Smith's application for prohibition was heard by the High Court of Australia.

The central legal issues before the Court were whether the court-martial had jurisdiction to try Smith on the charge of mutiny, given his discharge from the forces, and whether the charge itself was legally valid. Specifically, the Court had to determine if a discharged soldier undergoing detention could be considered a person subject to military law for the purposes of committing mutiny in His Majesty's Forces, and if the provisions of the Defence Act and the Army Act, as applied to such individuals, were consistent with the Australian Constitution. The Court also considered the effect of rulings by the Judge Advocate-General on the proceedings.

The High Court, in a majority decision, held that section 158(2) of the Army Act (Imp.) rendered a soldier sentenced to detention subject to the Army Act during the term of his sentence, notwithstanding his discharge from the forces. This meant that such individuals remained subject to military law and could be tried by court-martial for offences committed during detention. The majority reasoned that the purpose of section 158(2) was to maintain discipline and ensure that the Army Act continued to apply to these individuals, treating them as if they were still subject to military law for the purpose of punishment. However, a division emerged on the question of whether prohibition lay. The majority found that the charge, as framed, alleged a mutiny among persons who were no longer members of His Majesty's Forces, and therefore did not constitute a mutiny "in His Majesty's forces" as required by section 7(3) of the Army Act.

Consequently, the majority of the High Court ordered that the writ of prohibition should issue, preventing the court-martial from proceeding with the trial on the charge as laid. Latham C.J. and Starke J. dissented, holding that the court-martial did have jurisdiction and that the order nisi for prohibition should be discharged.