The US Supreme Court on Friday took the dramatic step of overturning the landmark 1973 Roe vs Wade ruling that recognised a woman's constitutional right to an abortion and legalised it nationwide, handing a momentous victory to Republicans and religious conservatives who want to limit or ban the procedure.

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 vs Wade decision that allowed abortions performed before a fetus 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.

Read: Norma McCorvey, ‘Jane Roe’ of landmark abortion ruling, die

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 fetal 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 vs Wade recognised that the right to personal privacy under the US constitution protects a woman's ability to terminate her pregnancy.

The Supreme Court in a 1992 ruling called Planned Parenthood of Southeastern Pennsylvania vs Casey reaffirmed abortion rights and prohibited laws imposing an “undue burden” on abortion access.

Chief Justice John Roberts denounced the May 2 leak of Justice Samuel Alito's draft opinion in the case and announced an investigation to identify the culprit.

Supreme Court leaks are extremely rare, especially concerning internal deliberations before a ruling is issued.

Following the leak, Biden condemned the overturning of Roe as a “radical” step and urged Congress to pass legislation protecting abortion access nationally.

Thousands of people rallied for abortion rights in Washington and other cities after the leak, including some protesters at the homes of some conservative justices.

A California man armed with a handgun, ammunition, a crow bar and pepper spray was arrested near Justice Brett Kavanaugh's Maryland home on June 8 and charged with attempted murder.

The justices in 2016 struck down a Texas law imposing strict regulations on abortion facilities and doctors.

The justices in 2020 struck down a Louisiana law that similarly placed restrictions on doctors who perform abortions. But the court has become more conservative in recent years with the addition of three appointees made by former US president Donald Trump.

Since 2018, the court lost two champions of abortion rights. Liberal Justice Ruther Bader Ginsburg died in 2020, being replaced by Amy Coney Barrett, who as an academic before joining the judiciary signaled support for overturning Roe.

Justice Anthony Kennedy, a conservative who sometimes sided with the liberal justices on social issues such as abortion and LGBT rights, retired in 2018 and was replaced by Kavanaugh. Kennedy was part of the majority in the 1992 decision and voted to strike down the Texas abortion restriction in 2016.

Justice Neil Gorsuch in 2017 replaced the late conservative Justice Antonin Scalia, who was an abortion opponent.

Opinion polls show a majority of Americans support abortion rights. But overturning Roe has been a goal of anti-abortion activists and Christian conservatives for decades, with annual marches in Washington including in January of this year.

The number of US abortions increased by eight per cent during the three years ending in 2020, reversing a 30-year trend of declining numbers, according to data released on June 15 by 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 — 15-44 — and stood at 13.5 per 1,000 in 2017 before increasing to 14.4 per 1,000 women by 2020.

In 2020, there were 930,160 US abortions, with 20.6pc of pregnancies ending in abortion in 2020, up from 18.4pc in 2017. Mississippi experienced a 40pc increase in abortions performed from 2017 to 2020.

Globally, abortion rights generally have been increasing. The UN World Health Organisation said around 73 million abortions take place globally each year, including 29pc of all pregnancies.