Convicted killer Gregory Wayne Kable has won his case against the state government for unlawful imprisonment and is entitled to compensation, the Court of Appeal has found.

Mr Kable stabbed his wife to death in their house on September 5, 1989, following a bitter custody dispute over their two children.

Gregory Wayne Kable ... won his case. Credit:Steve Lunam

He pleaded guilty to manslaughter and was jailed for a minimum of four years.

While in jail, he wrote threatening letters to the relatives of his dead wife. In response, the government passed a law enabling authorities to keep Mr Kable behind bars for a further six months. He was freed in 1995.

The High Court found the legislation unconstitutional.

In the Court of Appeal this morning, the five judge appeal panel gave judgment for Mr Kable against the state for unlawful imprisonment. He was also awarded costs.

The matter was sent back to the Common Law division of the Supreme Court to assess the amount of damages Mr Kable will receive.