The already divisive abortion debate in the US has been further riven after Arizona’s top court upheld a Civil War-era law banning the procedure for the vast majority of women.

The law, which dates from 1864 – about 50 years before statehood and women’s suffrage – further restricts reproductive rights in a US state where terminating a pregnancy was already barred at 15 weeks of gestation.

On Tuesday (US time), the Arizona Supreme Court ruled 4-2 in favour of an anti-abortion obstetrician and a county prosecutor who pressed to implement the 160-year-old statute after the state’s Democratic attorney-general declined to do so.

States were given the go-ahead to adopt such bans after the conservative-majority US Supreme Court in June 2022 overturned its landmark 1973 ruling in Roe v Wade, which had made access to abortion a constitutional right across the US.

Arizona Justice John Lopez, who like all of the state Supreme Court’s members was appointed by a Republican governor, wrote that the state’s legislature “has never affirmatively created a right to, or independently authorised, elective abortion”.

“We defer, as we are constitutionally obligated to do, to the legislature’s judgment, which is accountable to, and thus reflects, the mutable will of our citizens,” Lopez wrote.

The state high court ruled the 19th-century law could be enforced prospectively. But it stayed implementation of its decision for 14 days to allow the parties to raise any remaining issues at the trial-court level.

Arizona Attorney-General Kris Mayes, a Democrat, called the ruling “unconscionable and an affront to freedom”, and stressed that she would not prosecute any doctor or woman under the “draconian law”.

“Today’s decision to reimpose a law from a time when Arizona wasn’t a state, the Civil War was raging, and women couldn’t even vote will go down in history as a stain on our state,” she said.

Planned Parenthood Arizona, which offers abortions at its clinics, said it would continue to provide those services “for a short period of time” under a 2022 state court order barring immediate enforcement of the 1864 law.

That injunction, according to the organisation, remains in effect until 45 days after the state Supreme Court formally issues its ruling. That usually takes several weeks.

Tuesday’s decision marked the latest legal setback for US abortion rights, following a ruling last week by the Florida Supreme Court that cleared the way for a Republican-backed law banning abortion after six weeks of pregnancy to take effect.

It is expected to further supercharge the fight over abortion rights in the US, this time in a state that is expected to be a key battleground in November’s presidential election.

President Joe Biden, a Democrat whose re-election bid is widely seen as gaining from a backlash to abortion restrictions since Roe was overturned, called the Arizona ruling the “result of the extreme agenda of Republican elected officials who are committed to ripping away women’s freedom”.

“Millions of Arizonans will soon live under an even more extreme and dangerous abortion ban, which fails to protect women even when their health is at risk or in tragic cases of rape or incest,” he said.

California governor Gavin Newsom, a Democrat, said on the social media platform X that his neighbouring state “remains ready to help Arizonans access reproductive health care.”

Fourteen other states have banned nearly all abortions since the US Supreme Court’s 2022 ruling.

Republican presidential candidate Donald Trump said this week access to abortion should be determined by the states, and stopped short of proposing a national ban that could imperil his chances with swing voters in November.

-with AAP