The US Supreme Court has ended the right to abortion in a seismic ruling that shreds half a century of constitutional protections on one of the most divisive and bitterly fought issues in American political life.

The conservative-dominated court overturned the 1973 Roe v Wade ruling that recognised a woman's constitutional right to an abortion and legalised it nationwide.

More recently, in a 1992 ruling called Planned Parenthood of Southeastern Pennsylvania v Casey, the Supreme Court reaffirmed abortion rights and prohibited laws imposing an "undue burden" on abortion access.

But today it ruled: "The Constitution does not confer a right to abortion; Roe and Casey are overruled; and the authority to regulate abortion is returned to the people and their elected representatives."

The ruling restores the ability of states to pass laws prohibiting it - by erasing abortion as a constitutional right.

Twenty-six states are seen as either certain or likely now to ban abortion. Mississippi is among 13 states already with so-called trigger laws designed to ban abortion if Roe v Wade were to be overturned.

Abortion is likely to remain legal in liberal states. More than a dozen states currently have laws protecting abortion rights.

Numerous Republican-led states have passed various abortion restrictions in defiance of the Roe precedent in recent years.

Today's Supreme Court judgment handed a momentous victory to Republicans and religious conservatives who want to limit or ban the procedure.

Anti-abortion demonstrators hug outside the US Supreme Court after ruling was made public

The court, in a 6-3 ruling powered by its conservative majority, upheld a Republican-backed Mississippi law that bans abortion after 15 weeks.

The justices held that the Roe v Wade decision that allowed abortions performed before a foetus would be viable outside the womb - between 24 and 28 weeks of pregnancy - was wrongly decided because the US Constitution makes no specific mention of abortion rights.

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A draft version of the ruling indicating the court was likely to overturn Roe was leaked in May, igniting a political firestorm.

Mississippi's law had been blocked by lower courts as a violation of Supreme Court precedent on abortion rights.

Jackson Women's Health Organisation, the only abortion clinic remaining in Mississippi, challenged the 2018 law and had the support of Democratic President Joe Biden's administration at the Supreme Court.

The law allows abortions when there is a "medical emergency" or a "severe foetal abnormality", but does not have an exception for pregnancies resulting from rape or incest.

A federal judge in 2018 struck the law down, citing the Roe precedent. The New Orleans-based 5th US Circuit Court of Appeals in 2019 reached the same conclusion.

Roe v Wade recognised that the right to personal privacy under the US Constitution protects a woman's ability to terminate her pregnancy.

A pro-choice supporter cries outside the US Supreme Court today

As a result of today's ruling, women with unwanted pregnancies in large swathes of America may face the choice of travelling to another state where the procedure remains legal and available, buying abortion pills online or having a potentially dangerous illegal abortion.

Justice Samuel Alito, as expected, wrote the majority opinion that tossed out Roe as well as the 1992 decision upholding abortion rights in Planned Parenthood v Casey.

He was joined by Justices Clarence Thomas, Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett in agreeing the judgment.

The latter three justices are all Donald Trump appointees. Judge Thomas first voted to overrule Roe 30 years ago.

Asked in a Fox News interview whether he deserved some credit for the ruling, Mr Trump said: "God made the decision."

Judge Alito wrote: "We hold that Roe and Casey must be overruled.

"The Constitution makes no reference to abortion, and no such right is implicitly protected by any constitutional provision, including the one on which the defenders of Roe and Casey now chiefly rely - the Due Process Clause of the Fourteenth Amendment."

Meanwhile, three liberal West Coast states banded together to issue a joint pledge to defend abortion rights, in the wake of the Supreme Court's decision.

"The governors of California, Oregon and Washington today issued a Multi-State Commitment to defend access to reproductive health care, including abortion and contraceptives, and committed to protecting patients and doctors against efforts by other states to export their abortion bans to our states," a statement said.

Attendees at the National Right To Life Convention today in Atlanta, Georgia

Liberal judges dissent 'with sorrow for millions of American women'

The Supreme Court's three liberal justices - Stephen Breyer, Sonia Sotomayor and Elena Kagan - issued a jointly authored dissent.

"Whatever the exact scope of the coming laws, one result of today's decision is certain: the curtailment of women's rights and of their status as free and equal citizens," they wrote.

As a result of Friday's ruling, "from the very moment of fertilisation, a woman has no rights to speak of. A state can force her to bring a pregnancy to term, even at the steepest personal and familial costs," the liberal justices added.

Justices Breyer, Sotomayor, and Kagan condemned the ruling as "catastrophic" and legally flawed - one that would let states force a woman to bring a pregnancy to term, and in some states, "to bear her rapist's child".

They noted: "With sorrow - for this Court, but more, for the many millions of American women who have today lost a fundamental constitutional protection - we dissent."

Crowds of anti-abortion activists, who had gathered outside the Supreme Court in Washington DC for days, erupted in cheers as news of the ruling spread.

"I'm ecstatic," said Emma Craig, 36, of Pro Life San Francisco. "Abortion is the biggest tragedy of our generation and in 50 years we'll look back at the 50 years we've been under Roe v Wade with shame."

The number of US abortions increased by 8% during the three years ending in 2020, reversing a 30-year trend of declining numbers, according to the Guttmacher Institute, a research group that supporters abortion rights.

The US abortion rate peaked in 1980, seven years after the Roe ruling, at 29.3 abortions per 1,000 women of child-bearing age (between 15 and 44).

It stood at 13.5 per 1,000 in 2017 before increasing to 14.4 per 1,000 women by 2020. There were 930,160 US abortions in 2020.