Couples have brushed aside criticism and a legal challenge to wed under Australia’s first same-sex marriage law.

The bride wore white and so did her wife.

Corinna Peck and Stacey Cowen were among some 15 couples to tie the knot in Canberra on Saturday as Australia’s first same-sex marriage law came into play.

But while the outfits were bright and newlywed smiles beamed across the nation’s capital, a dark cloud was hanging over the future validity of the same-sex unions.

On Thursday the High Court will rule if the ACT’s Marriage Equality Act, passed in October, is at odds with Commonwealth law and therefore invalid.

The threat didn’t dampen the enthusiasm of groom Ivan Hinton who vowed to make partner Chris Teoh his “lawful wedded husband”.

“There should never be any rule in this country that disrespects the commitment that two people like us wish to express to one another,” Mr Hinton told reporters after his wedding.

Ceremonies kicked off at 12.01am (AEDT) with two couples rushing to become Australia’s first legally-recognised “husbands”.

Australian Marriage Equality director Rodney Croome attended Mr Hinton’s marriage and afterwards highlighted the historic nature of Saturday’s events.

“In years to come people will look back and think `what an historic moment that was,’ but also, `why did it take us so long to recognise the wonderful ordinariness of the love, (the) commitment of same-sex relationships?’,” Mr Croome said.

The Australian Christian Lobby has criticised the ACT law, claiming it damages the institution of marriage.

“We hear about equal love all the time but we don’t hear about what it means for children,” Lobby spokesman Lyle Shelton told Sky News.

“Same-sex marriage means same-sex parenting, that means necessarily taking a child from its biological mother or father and giving it to someone else.”

ACT Chief Minister Katy Gallagher defended the law and sent a message to critics: “the world will go on”.

“This doesn’t effect those people who don’t agree with it. It doesn’t change their life, it doesn’t change their relationships. This is all about making sure everyone is treated equally before the law,” she said.

Ms Gallagher insisted that the community response, including from religious groups, had been overwhelmingly supportive.

Australian Greens senator Sarah Hanson-Young congratulated the newlywed couples and thanked them for being part of an important first step to change.

“This is how laws change, it is how communities evolve, it is how social change happens, when individuals put themselves forward,” she said.

“I think it’s time that politics put aside the views of others and allowed couples right across this country to have their love celebrated and accepted and recognised.”

The ACT government said 47 couple have registered an intent to marry under the new law.