The ACT Legislative Assembly passed Australia’s first same-sex marriage law in October, prompting a High Court challenge by the federal government.

The territory government on Monday filed a response to a Commonwealth submission which had argued the ACT same-sex marriage law was unconstitutional.

The ACT’s legal team said that territory-based same-sex marriage laws could operate concurrently with the federal Marriage and Family Law Acts.

While Commonwealth law prevented the recognition of same-sex marriages solemnised overseas, it did not prohibit same-sex marriages from being created in Australia.

“At the present time, the Commonwealth has not exhausted its legislative power with respect to either recognising or prohibiting same sex marriage,’’ the submission said.

“The Marriage Act is concerned only with marriage as described by [section five] of the Act, but not otherwise.

“The Commonwealth has exercised its legislative power in a limited manner to refuse the recognition of foreign same-sex marriages but has gone no further. The Marriage Act does not speak to same sex marriages solemnised in Australia.’’

The ACT argued that Commonwealth law prohibited bigamous, polygamous, involuntary and under aged marriage.

But there was no express prohibition on same-sex marriages.

“Importantly, the same sex marriages are not designated as “prohibited relationships,’’ the ACT submission said.

The ACT’s legal team includes Solicitor-General Peter Garrisson, SC, and Kate Eastman, SC.

In its submission to the court, the Commonwealth argued that same-sex couples felon the wrong side of a legal “binary divide’’ and must remain unmarried.

The Commonwealth has until November 29 to respond to the territory’s submission.

The case will be heard by the full bench of the High Court on December 3 and 4.

Due to notice requirements, the ACT’s first legal same-sex weddings are not due to occur until December 7.