Private mining company Cascade Coal and its former director Travers Duncan, along with listed company NuCoal, had asked the court to overturn NSW laws cancelling the companies' multimillion-dollar licences.

The laws were passed on January 30 last year after the Independent Commission Against Corruption said the licences were "so tainted by corruption" they should be "expunged or cancelled".

The High Court ruled unanimously on Wednesday that the state of NSW was acting within its powers by cancelling the licences. 

The ICAC found Mr Obeid and his middle son, Moses, corruptly agreed with former mining minister Ian Macdonald to create a coal tenement over the Obeids' Bylong Valley property.

Cascade Coal previously held two exploration licences, including one over the property owned by the family of Mr Obeid.

Mr Duncan and his business associates – among the founding investors in Cascade Coal – were found to have acted corruptly by concealing the Obeid family's involvement in the tenement from officials.

Mr Macdonald was also found to have acted corruptly by granting an exploration licence at Doyles Creek to a company chaired by his "mate", former union boss John Maitland. Listed company NuCoal subsequently acquired the licence.

NuCoal had said the NSW laws "stigmatise" the companies and their "mum and dad" shareholders have suffered even though they were not a party to any wrongdoing found by the ICAC.

The ICAC had recommended the government consider compensating "any innocent person" affected by the laws, but the former O'Farrell government decided against it.

The companies and Mr Duncan had argued that the NSW Parliament strayed outside its powers by passing laws that amount to a determination and punishment of guilt. They said this was an exercise of judicial power that could only be exercised by the courts.

But all seven judges of the court said the Act cancelling the licences was "not an exercise of judicial power" by the state Parliament.

"It precludes no future determination by a court of past criminal or civil liability," the court said, adding the people found by the ICAC to have acted corruption "remain subject to the ordinary processes of the law."

Being deprived of valuable assets without compensation was a detriment but it could not be equated with a punishment, the unanimous judgment said.

The High Court ordered the mining companies and Mr Duncan to pay the state of NSW's costs of the legal battle.

Acting Premier Troy Grant said the decision "ensures the ongoing integrity of our resource allocation process, and draws a line under this sorry saga".

NuCoal chairman Gordon Galt said the High Court action was just one of three actions the company was pursuing to "seek legal redress for our innocent shareholders".

Mr Galt said the company "naturally" was disappointed it had not prevailed in the High Court but it was also seeking "judicial review in the Supreme Court of NSW to challenge the process undertaken by ICAC". It was also pursuing claims on behalf of overseas investors under various Free Trade Agreements.

with Matthew Knott and Nicole Hasham