NSW unions are launching a High Court challenge to the state government's electoral donation laws, arguing they breach constitutional rights of freedom of political expression.
The laws, passed by the NSW parliament last year, ban all but individuals from donating to political parties.
Mark Lennon, secretary of Unions NSW, which is leading Monday's court action, says the laws hinder working people from expressing their political views.
"If they're allowed to stand, the O'Farrell government's electoral donation laws will muzzle debate and silence the voice of working people in NSW," he said.
"Our High Court action is about the right of working people to ensure their collective voice is heard."
He said the laws were a cynical attempt by the government to undermine the political strength of its opponents.
The laws ban unions from paying affiliation fees to political parties, combine caps on election spending for political parties and affiliated unions and ban peak councils such as Unions NSW from levying its affiliates to run movement-wide election campaigns.
The NSW Greens warn the court challenge could have the unintended consequence of returning the state to the days when millions of dollars flowed to political parties from vested corporate interests.
Greens MP John Kaye said the outcome could "reopen the floodgates to corporate donations and the corrupting influence they had on political parties".
"It would be unfortunate if the unions' case delivered a springboard for the developers and the alcohol, tobacco and gambling industries or other corporations to once again corrupt state politics," he said in a statement.
