The ACT Government will amend its same-sex marriage legislation to give it more chance of surviving a High Court challenge.

The Government plans to pass a bill legalising gay marriage tomorrow with the support of Greens MLA Shane Rattenbury.

But some pro-marriage equality groups and constitutional law experts raised concerns the laws could be struck down if the bill was not re-worded to create a separate status of marriage for same-sex couples.

The Federal Government has already flagged it will challenge the laws in the High Court.

In response, the Government will put forward some amendments to clarify the scope of the laws when it is debated in the Legislative Assembly tomorrow.

ACT Attorney-General Simon Corbell says the bill will be renamed the Marriage Equality Same-Sex Bill. It had been titled the Marriage Equality Bill.

"These are very much issues of language rather than substance. But we are having regard to the fact that language may be a factor that may be argued in court," he said.

"It doesn't change the substance of the scheme for the majority of the legislation."

Will the ACT's marriage equality bill survive a High Court challenge? ABC Fact Check takes a look.

But the changes to wording mean the laws will no longer apply to people who identify as neither male nor female.

"We regret that that change is being made but we recognise that the views of a number of constitutional experts are that we should put that issue beyond doubt in the terminology that's applied in our bill," Mr Corbell said.

"If our bill is upheld we will certainly move at a later date to expand its scope."

Chief Minister Katy Gallagher says the changes will give the bill the best possible chance of surviving a High Court challenge.

"We know we're going to face a very strong response from the Commonwealth in pursuing this matter to the High Court," she said.

"We've chosen to be inclusive of the opinions of those who have fought long and hard for this social change ... so we're making some minor amendment along those lines."

'Unprecedented solidarity'

Meanwhile leaders of eight of Canberra's religious faiths met today to present a united front against the legislation.

The meeting will include leaders of the Jewish, Muslim, Roman Catholic, Anglican, Westminster Presbyterian, Seventh-Day Adventist and The Church of Jesus Christ of Latter-Day Saints congregations.

Organiser Rabbi Shimon Cowen says it is the first time all of the faiths have come together over an issue in Canberra.

He says the Government's push for gay marriage rights ignores the views of large sections of the community.

"We will hope that this will cause the Government to realise that it cannot monolithically impose such a drastic change on the population which is largely composed of faiths which uphold traditional marriages," he said.

"Federally, and in all other states where this has been tempted, it did not succeed."

*Editor's note: Initially this story incorrectly stated the legislation amendments remove references to all transgender couples. The changes only remove references to people who identify as neither male or female.