The federal parliament has lifted a 25-year-old ban that prevented the territories from making voluntary assisted dying laws.
Every state in Australia has already legalised voluntary euthanasia.
However, in 1997, the Commonwealth imposed a veto on the Northern Territory and the ACT, specifically barring them from doing so.
Thursday's Senate vote ends that ban, paving the way for the two territories to debate and pass their own laws.
The chamber and public gallery broke out into applause as senators agreed to repeal the ban, without a formal count of votes for and against.
Among the onlookers were several ACT MLAs, including Chief Minister Andrew Barr.
Former NT chief minister Marshall Perron was also in the gallery.
Mr Perron's Country Liberal Party government had introduced the world's first legal euthanasia scheme in 1995, before then federal Liberal backbencher Kevin Andrews led the Commonwealth push to abolish it.
Thursday's Senate vote followed hours of debate across several sittings, involving almost all senators and, earlier, many MPs.
The main parties had allowed parliamentarians to vote according to their conscience.
It was the fourth attempt to revoke Mr Andrews's ban on the territories, following earlier, unsuccessful efforts in 2008, 2010 and 2018.
Mr Perron thanked Prime Minister Anthony Albanese for "doing what his five predecessors didn't do".
"And that's facilitate the debate on returning power to the territories," he said.
"There has been a bill before parliament to do exactly that, continuously now, for 18 years."
Advocates highlight 'unconscionable' divide
Labor had promised before this year's election that it would allow a debate on the longstanding ban.
Independent ACT senator David Pocock had also pledged to push for a vote on territory rights.
Ultimately, two Labor backbenchers — Canberra's Alicia Payne and Darwin's Luke Gosling — introduced the bill that eventually passed through parliament.
Television producer and comedian Andrew Denton, who founded the euthanasia advocacy group Go Gently, was on hand to watch the final vote.
He expressed "deep gratitude" to parliamentarians, "on behalf of all advocates, and particularly those who died painfully or had loved ones who died painfully".
"It is unconscionable that here, in the ACT, somebody dying of cancer does not have the same end-of-life choices as somebody living less than 30 kilometres away in Queanbeyan."
During the debate, NT Labor senator Malarndirri McCarthy said past justifications to intervene in and control the territories made little sense today.
"Yes, we do have a small population in the Northern Territory, but we have big hearts," she said.
"We have great thinkers, we excel at so many levels."
Senator McCarthy said that since Mr Perron introduced his world-first legislation in 1995, the NT "has grown, exponentially, in skills, and knowledge, and ability to make its own decisions".
"Why is it we are constantly told we cannot make decisions for ourselves?"
ACT to draft laws, but NT to hold off
Mr Barr described the vote as "humbling", saying Canberrans had waited years for the intervention to be overturned.
"It's been a long journey to get to this point," he said.
His government would begin consulting on an ACT euthanasia policy earlier next year, with the aim of tabling draft laws later in 2023, he said.
"It will kick off a process … that will be considered and thorough, that will involve issuing a discussion paper and seeking community feedback on the exact nature of voluntary assisted dying laws for the ACT," he said.
Mr Barr said it was likely the Legislative Assembly would debate those laws late next year or early in 2024, and that any vote would be a conscience vote.
However, the NT government is less hurried.
The territory's new chief minister, Natasha Fyles, has indicated that her government will not prepare euthanasia legislation during this parliamentary term.
The next NT election is just under two years away.
'Significant and historic moment'
A majority of Coalition and Labor parliamentarians had backed Mr Andrews's bill over many years, blocking attempts to repeal it.
However, support for the territories ban waned as state governments began to adopt voluntary assisted dying laws.
While some parliamentarians from both main parties opposed Ms Payne and Mr Gosling's bill, it won backing across the political spectrum.
Labor senator Katy Gallagher had campaigned to remove the ban for years, including when she was chief minister of the ACT.
"This is a really significant and historic moment, and one that a lot of people have fought a long time to witness," she said.
"I know how much the restoration of territory rights matters to Canberrans."
Senator Pocock thanked the "thousands of communities" who had refused to let the bill "fall off the national agenda".
"Dignity, freedom and choice shouldn't end at the borders we draw on a map — we are all Australians and we all deserve the same democratic rights," he said.
"Our community in the ACT can now start having the conversation on whether a voluntary assisted dying scheme is right for us."
