He says a looming High Court challenge by the Abbott government to the ACT's same-sex marriage laws will not stop him from marrying his partner Christopher, who shares a last name with Brendon, once the bill passes the Legislative Assembly.

Brendon and Christopher entered a civil union in March. But it is a marriage that they want, ''to be treated like everyone else''.

''We fully intend to get married as soon as it's passed regardless of whether the legislation is repealed or not,'' Mr Condon said. ''We think we're like everyone else and should be treated like everyone else.

''We want to show our families we love each other a lot, and that our commitment is important to us.''

Attorney-General George Brandis confirmed the legal challenge on Thursday, because the legislation was ''a threat'' to the ''well-established position'' that marriage was a Commonwealth matter.

But Chief Minister Katy Gallagher said on Friday the directive to challenge the laws had come from Prime Minister Tony Abbott.

''Certainly [Senator] Brandis made it clear he was acting on instructions from the Prime Minister,'' Ms Gallagher said.

Mr Condon said he believed couples would not be deterred by the prospect that their marriages could become invalid if the High Court challenge is successful. ''I expect people will be going out there very early and getting married - similar to what we saw in California with Proposition 8,'' he said.

Darlene Cox said she and her partner, Liz Holcombe, would lodge formal notice of their intent to marry on the day the bill is passed.

''Liz and I want to have the opportunity to be married, even though we understand that the Commonwealth will challenge the law in the High Court. There is no guarantee that the Commonwealth case will be successful.''

In Melbourne, Nicci Reid and her partner, Nicole Weightman, are planning to travel to Canberra to marry after the laws are passed.

They're planning a family and Ms Reid said: ''We want to bring kids into a world with equality.

''It's a shame if after the challenge it's taken out. It's a chance for people to have a right they've waited so long for, and a government is going to come in and squash it.''

Chapman resident Rohan McCarthy married his husband, Darren Gill, in New Zealand at the end of last month. He said they didn't want to wait for the ACT laws, but will consider a second ceremony if they survive the High Court challenge.

''I certainly would be upset for gay and lesbian couples to have their marriages annulled if the High Court ruled the law was inconsistent.

''But I think it's important that the gay and lesbian community not let this issue die.''