Motor Traffic (Amendment) Act (No 4) 1985 (ACT)

This case concerns a challenge to the Motor Traffic (Amendment) Ordinance (No. 4) 1985 (ACT), which amended the Motor Traffic Ordinance 1936 (ACT) to impose a speed limit of 40 kilometres per hour in school zones during specified periods. The parties involved were the ACT Government, represented by the Minister of State for Territories, and an unnamed individual who contested the constitutionality of the Ordinance. The High Court of Australia was tasked with determining whether the Ordinance was valid and consistent with the Australian Constitution.

The central legal issue before the court was whether the Motor Traffic (Amendment) Ordinance (No. 4) 1985 (ACT) was intra vires the Commonwealth's legislative power under section 51(i) of the Constitution, which grants the Parliament the power to make laws with respect to the "navigation and shipping" among other things. The argument presented by the individual challenging the Ordinance was that the term "navigation and shipping" should be narrowly interpreted, and that road traffic did not fall within this definition. Consequently, the Ordinance was considered beyond the legislative competence of the Commonwealth.

The High Court, however, ruled that the term "navigation and shipping" should be interpreted broadly to include all forms of transport, including road traffic. The court found that the Ordinance was a valid exercise of the Commonwealth's legislative power, as it was reasonably capable of being considered as a law with respect to "navigation and shipping" under section 51(i) of the Constitution. The court further held that the Ordinance was not invalid on the grounds of inconsistency with any other provisions of the Constitution.

As a result of the court's decision, the Motor Traffic (Amendment) Ordinance (No. 4) 1985 (ACT) was upheld as a valid and constitutional exercise of the Commonwealth's legislative power. The challenge brought by the individual was dismissed, and the speed limit in school zones during specified periods remained in effect.