Prime Minister Tony Abbott speaking on 3AW on Wednesday

Prime Minister Tony Abbott speaking on 3AW on Wednesday Photo: Penny Stephens

The Commonwealth government has lodged a writ of summons in the High Court challenging the validity of the ACT's same sex marriage laws.

A spokesman for the High Court of Australia confirmed the writ was lodged on Wednesday, just 24 hours after the laws were passed by the ACT Legislative Assembly. 

The writ says the new laws are inconsistent with the Commonwealth Marriage Act and the Family Law Act.

ACT Chief Minister Katy Gallagher said the move was expected, and ACT Attorney-General Simon Corbell said the Commonwealth was being patronising and rejected the call for an expedited hearing. He said the laws had a "high chance of surviving".

A High Court hearing could be held as soon as next week. The ACT Government was called to file its defence by October 30 and the proceeding filed for further directions on October 31.

"The Commonwealth contends that the proceeding should be heard at the earliest possible date, to reduce or avoid the uncertainty that will hang over the validity of the ACT Marriage ACT," the writ says.

"That uncertainty is exacerbated to the extent that persons may wish to enter into marriages under the ACT Marriage Act before its validity is determined."

The Australian Government Solicitor has asked for the matter to be heard by the full court and is seeking a hearing Thursday or soon thereafter.

"There would be immediate adverse effects for persons whose marriages would be ineffective if the ACT Marriage Act is found invalid," the writ says. "The status of marriage has a weight and a significance beyond its legal consequences."

A proposed timeline in the writ includes a one or two day hearing of the full court as early as November 26.

ACT Attorney-General Simon Corbell dismissed the call from the Federal Governemnt for same-sex couples to hold off marrying in the territory until the law was tested in the High Court.

“I would say to the Prime Minister and to Senator Brandis that their comments are patronising . . . in the extreme," Mr Corbell said.

“The only people causing distress to same-sex couples are the Prime Minister and [Federal Attorney-General] Senator [George] Brandis."

Mr Corbell was confident that the law had a strong chance of surviving the challenge.

“I’m very confident that our act is soundly-based and has the potential to give us strong legal arguments to put," he said.

“Ultimately it will be a matter for the court to decide. We are in uncharted waters. This will be a very significant High Court case but we will present the best arguments on behalf of our law."

Mr Corbell said the ACT would comply with any timeline set by the court but did not believe that the case should be expedited. He said potential additional parties to the case should be given time to prepare.

“We believe it’s important that parties who wish to be heard are given the opportunity to porterly prepare," he said.

The ACT’s defence would be funded from existing government legal budgets.

Mr Corbell said external counsel had been employed by the territory for the case. But he declined to name the counsel.

“That will become apparent," he said.

Earlier, Prime Minister Tony Abbott defended a challenge to ACT same-sex marriage laws as a constitutional matter, not a moral issue.

The ACT Legislative Assembly passed historic same-sex marriage laws on Tuesday.

Advising same-sex couples wishing to marry in the ACT to wait until a High Court challenge is resolved, Mr Abbott said the federal government had constitutional responsibility for marriage. 

"It is not a question of being for or against gay marriage - it’s a question of adhering to the constitution," Mr Abbott told Fairfax Radio in Melbourne.

"If, as I think, the ACT legislation turns out to be invalid under the Constitution then those marriages wouldn’t be valid," he said.

"So I would suggest to people who would like to be married under the ACT legislation hold on until its validity is tested."

Mr Abbott said there were a range of views about same-sex marriage within the Coalition government and amongst his Cabinet members.

He said the views of Attorney-General George Brandis could be more progressive than others.

"But the job of the attorney is to uphold the constitution," he said.

Senator Brandis, who has maintained a low-profile since recent criticism of his use of parliamentary entitlements for personal travel and the fit out of his Parliament House office, would not comment when asked about the federal government's chances in the High Court.

"I don’t think it’s wise for people to comment on proceedings before the High Court," he told reporters in Canberra on Wednesday.

"One of my predecessors, Ms Roxon, made a habit of offering a running commentary on litigation in which the Commonwealth was involved. I thought that was extremely foolish and it's not something I need to do."

He issued a statement on Tuesday and said he would seek an expedited hearing in the High Court - in part to minimise any ''distress'' the overturning of the laws might cause to couples who had already married.

Read the full writ of summons provided by the High Court of Australia.

Writ of summons Cth v ACT.pdf