The High Court in Canberra has thrown out the ACT’s controversial same-sex marriage laws.
A total of 27 couples including some from interstate have used the law to marry since it came into effect last weekend.
Same-sex couples who married over the last few days are now expected to have their marriages annulled.
The High Court delivered the decision early to give certainty to those wanting to use the law, but it might be some time before a full judgement is released.
The Federal Government opposed the territory law, saying it was inconsistent with the Federal Marriage Act, which defines marriage as between a man and a woman.
It argued that inconsistency made the laws unconstitutional.
The ACT tried to get around the inconsistency saying the new law only dealt with a new category of marriage, between same-sex couples and it could sit alongside the federal law.