Kable v Director of Public Prosecutions for NSW (1996) 189 CLR 51; [1996] HCA 24 was a significant case decided in the High Court of Australia regarding the Chapter III rights in the Constitution and the scope of power of state courts vested with federal jurisdiction.
This legislation was closely modelled on a law passed in Victoria, the Community Protection Act 1990 (Vic), which was enacted to authorise 'preventive detention' for Garry David.
Kable whilst in gaol sent threatening letters to the people who denied him access to his children aged four and two years. After a sharp separation from his children to prison the letters were written whilst in prison in the first 12 months after being denied access to his children. He was subsequently charged and sentenced to an additional 16 months for writing the letters in 1990. Four years later and granted no parole his release from gaol coincided with a state election campaign, in an environment where, allegedly, voters were concerned about "law and order". Legislation was subsequently passed through parliament naming him explicitly. Early in 1995, Justice Levine of the Supreme Court made an order under the Community Protection Act, in respect of Kable, requiring that he be detained for a period of six months. Kable appealed that decision, and his appeal was dismissed by the NSW Court of Appeal in Kable v Director of Public Prosecutions (1995) 36 NSWLR 374. It was from this decision that the appeal was brought to the High Court, on grounds of constitutional invalidity.
The High Court held that the law was unconstitutional, and in the process construed a limitation on the powers of state courts vested with federal jurisdiction under Chapter III of the Constitution. They held that Chapter III, particularly section 71 purports to vest federal judicial power in the Supreme Court of New South Wales. The Act vested in the Supreme Court powers that were incompatible with the exercise of judicial power of the Commonwealth, that is, the law required the Supreme Court to exercise a power incompatible with its role in the federal judiciary.
Note that this decision's principles have been recently been revisited in narrow and arguably restrictive terms in the cases of Baker v The Queen and Fardon v Attorney-General (Qld).