The High Court’s judgment in the landmark case of Kable v Director of Public Prosecutions (NSW)  HCA 24 marked an important extension of a particularly Australian concept of the independence of the judiciary from the federal level to the state level.
The case concerned Gregory Kable, a New South Wales man who plead guilty to manslaughter in August 1990, following the death of his wife. He was imprisoned for five years. During that time, he wrote a number of threatening letters to members of his wife’s family, who were in custody of their two young children. He was charged with various relevant offences, but at the date of his release from jail, those charges had not yet been heard. The NSW Parliament took the not-very-extraordinary step of passing a law – the Community Protection Act 1994 (NSW) – that set up a system of preventative detention. However, the law was, extraordinarily, framed in a peculiar way. Section 3(3) of the Act read:
(3) This Act authorises the making of a detention order against Gregory Wayne Kable and does not authorise the making of a detention order against any other person.
The NSW Parliament had limited the extent of the system of preventative detention to just one person. On 30 December 1994, just before Kable’s imprisonment was about to end, Justice Hunter of the NSW Supreme Court made an interim detention order against Kable, for a period of three months. Just as that order was about to lapse, Justice Levine made a preventative detention order against Kable for 6 months. Kable appealed to the NSW Court of Appeal and lost. He subsequently was granted leave to appeal to the High Court. In the interim, the NSW DPP made a second application for a 6-month preventative detention order against Kable, and lost in August 1995. Kable was freed from custody, but remained liable to be re-imprisoned should a future application by the NSW DPP be successful.
At the High Court, Kable ran many arguments against the validity of the Act, including the argument that was ultimately successful: that the Act was inconsistent with the requirements of Chapter III of the Australian Constitution, as interpreted by previous cases like the Boilermakers’ case. According to that jurisprudence, Chapter III courts – that is to say, federal courts – were the only federal institutions capable of exercising federal judicial power, and they could not be invested with any non-judicial powers.
Up until this point, however, case law had not dealt with the question of whether similar limitations applied to non-Chapter III courts, that is, State courts. Since the court deciding whether or not to continue to detain Kable was the NSW Supreme Court – a State court – it was possible that legislation like the Community Protection Act might be valid at state level, even though it might not have been valid at the federal level.
However, the High Court found by majority (4:2) that it was not valid. The various judgments used various reasons for its invalidity, but the key point that has emerged from the Kable case, and been referred to in later preventative detention cases, is this: because the Constitution provides for an integrated judicial system in Australia, where State courts can exercise federal jurisdiction, the limitations placed on federal courts have some role to play in state courts too. Those limitations are not expressed the same way, because the High Court did not just translate the Constitution from federal to state level. Instead, what has emerged is the principle that the “institutional integrity” – to use the words of Justice Gummow – of state courts cannot be impaired by state legislatures or executives.
In other words, because they are, at times, repositories of federal judicial power, any moves that might impair the institutional integrity of state courts would therefore simultaneously impair federal judicial power. Accordingly, state courts must maintain the same kind of impartiality and public neutrality mandated for federal courts in the Constitution. Acts, like the Community Protection Act, that undermined this impartiality or public neutrality are thus invalid.
This Kable principle has been an important protection of individual liberty and the separation of powers in Australia over the last twenty years. In cases like Fardon, Totani, Wainohu, and Pompano, the Kable principle has been used to police the boundaries of state legislative powers, and protect individual liberty against unlawful deprivation. Although the exact boundary between community safety and personal liberty will always be contested, the High Court in Kable took an important step towards clarifying how the rule of law in Australia will deal with that complicated question.
— William Shrubb
‘Kable’s case and the rule of law‘, the Hon Kevin Lindgren AM QC