Ex Parte (No 1)

The case concerned charges laid against the defendant under the New South Wales Stock Act 1901. The defendant was accused of unlawfully introducing stock into New South Wales from Queensland, contrary to a proclamation issued under section 154 of the Act, and of failing to provide an inspector with full information regarding imported stock, as required by section 158(j). The defendant was convicted on both charges. Applications for writs of prohibition, initially made to the Supreme Court of New South Wales, were removed to the High Court of Australia due to questions concerning the constitutional powers of the Commonwealth and the State.

The central legal issues before the High Court were whether sections 154 and 158(j) of the Stock Act 1901 violated section 92 of the Commonwealth Constitution, which guarantees that trade, commerce, and intercourse among the States shall be absolutely free. Additionally, the court considered whether these State provisions were inconsistent with Commonwealth legislation, particularly the Quarantine Act, thereby rendering them invalid under section 109 of the Constitution, and whether they infringed upon the Commonwealth's exclusive power over customs under section 90.

A majority of the High Court, comprising Knox C.J., Gavan Duffy and Starke JJ., held that section 154 of the Stock Act 1901 did not contravene section 92 of the Constitution. They reasoned that while the section regulated the free flow of inter-State trade, its true nature and purpose were to protect the State's livestock from contagious and infectious diseases, which constituted a lawful exercise of the State's constitutional power. This was considered distinct from a direct regulation of inter-State commerce. Furthermore, Knox C.J., Gavan Duffy, Powers and Starke JJ. found that section 158(j) also did not violate section 92. The majority concluded that neither section 154 nor 158(j) was inconsistent with Commonwealth quarantine legislation, thus not invalid under section 109, nor did they impinge on the Commonwealth's customs power under section 90. Isaacs and Higgins JJ. dissented, with Isaacs J. arguing that section 158(j) was used to enforce an unlawful purpose under section 154, and Higgins J. asserting that section 158(j) burdened those crossing the border.

The High Court ordered that the rules nisi for prohibition be discharged in both cases, meaning the convictions against the defendant were upheld.