The Australian Capital Territory’s government has announced that it will introduce a bill this week to legalise same-sex marriage in the territory.

The territory’s minority Labor government will present its Marriage Equality Bill to the Legislative Assembly on Thursday. The proposal will make the Australian Capital Territory (ACT) the first Australian jurisdiction to introduce a marriage scheme for same-sex couples. The reform was promised by ACT Labor before last year’s territory election.

The laws will not have a residency requirement, meaning same-sex couples who do not live in the territory will be able to have a marriage ceremony in the ACT.

ACT Chief Minister Katy Gallagher said her government would once again “bring forward legislation that delivers equality for same-sex couples, legislation that promises them the right to marry.”

She added that marriage equality was a reform that a “growing proportion of Australians want made.”

“It is a matter of time,” the Chief Minister said. “We would prefer to see the Federal Parliament legislate for a nationally consistent scheme, but in the absence of this we will act for the people of the ACT. The Marriage Equality Bill 2013 will enable couples who are not able to marry under the Commonwealth Marriage Act 1961 to enter into marriage in the ACT. It will provide for solemnisation, eligibility, dissolution and annulment, regulatory requirements and notice of intention in relation to same-sex marriages.”

Ms Gallagher said her government was determined to remove discrimination against same-sex couples and their families, saying: “With this legislation, we will state loud and clear that all people have equal rights in our society and are treated equally by our laws.”

Same-sex couples living in the ACT have been allowed to register their partnerships since 2008 and hold civil partnership ceremonies since 2009, when the ACT became the first territory in Australia to introduce such legislation.

Constitutional experts have warned however that the territory’s new equal marriage legislation may not supersede the Federal Commonwealth Marriage Act 1961, which defines marriage as between a man and a woman.

Attorney General Simon Corbell believes the ACT law could withstand a High Court challenge, arguing that though the Commonwealth Act defines marriage as between a man and a woman, this means that the federal law doesn’t apply to same-sex couples and therefore states and territories can legislate for them.

Mr Corbell added that the legal advice provided to the ACT government in 2008, relating to its 2006 same-sex civil unions bill, supports this stance.

“The same legal principles apply and that’s why we’ve made that opinion public,” he told AAP on Monday.

However, University of Sydney constitutional law expert Helen Irving says the stronger argument is that the federal law intended to cover all kinds of marriage.

“When you have an act called the Marriage Act and it defines marriage as a certain type of union, that’s what marriage legally means,” she told AAP.

“It’s not an act that’s called the Heterosexual Marriage Act, which allows there to be the Same Sex Marriage Act and other types of marriage conceivably.”

While Professor Irving says she would be happy to see same-sex marriage laws, she doesn’t believe they can happen unless the federal law is also changed. She added that there was also a risk that the Federal Parliament could vote to overturn the ACT law if passed.

The ACT Legislative Assembly is expected to debate and vote on the proposed law in October.

Two weeks ago, Australians voted to reject former Labor Prime Minister Kevin Rudd – a supporter of equal marriage – in favour of his Liberal opponent, Tony Abbott.