The US Supreme Court has overturned the 1973 Roe v Wade case, which recognised the nationwide right to an abortion.
The decision is one of the most significant political developments in a generation and has far-reaching implications for millions of Americans.
The decision was handed down by the Supreme Court on Friday in a majority ruling of 5-4 . The court also voted 6-3 to uphold a Mississippi law banning abortion after 15 weeks of pregnancy.
What is Roe v Wade?
Roe v Wade is the landmark 1973 Supreme Court decision that established access to abortion as a constitutional right until the foetus is viable outside the womb, typically 22 to 24 weeks.
'Jane Roe' was an unmarried pregnant woman who filed a suit challenging abortion laws in Texas. The case was eventually heard by the Supreme Court, with judges ruling the Texas laws were unconstitutional.
This prevented all 50 states from being able to ban access to abortions outright.
How the US Supreme Court works
After an initial vote among the nine justices following an oral argument, one is assigned the majority opinion and writes a draft. It is then circulated among the justices.
At times, in between the initial vote and the ruling being released, the vote alignment can change. A ruling is only final when it is published by the court.
Last month, a draft of the opinion was leaked where it indicated that the Roe v Wade ruling would be overturned. On Saturday, the indication became final as the judgment was released.
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“Roe was egregiously wrong from the start,” Justice Samuel Alito wrote in the opinion.
"The Constitution does not confer a right to abortion ... The authority to regulate abortion is returned to the people and their elected representatives."
Four of the justices - Clarence Thomas, Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett - voted with Mr Alito in the conference held among the justices.
The four judges who supported Roe v Wade being upheld were: Stephen G. Breyer, Sonia Sotomayor, Elena Kagan and John G. Roberts, Jr.
How did we get here?
A segment of the population, particularly on the religious right, has never accepted the Roe v Wade ruling and campaigned to have it overturned ever since.
The Supreme Court's final opinion is the culmination of almost 50 years of activism around the argument from conservative Catholics and Evangelical Protestants.
After joining hands following Roe v Wade, their campaigning gained prominence over the following decades and gradually became a centrepiece for conservative politics.
The anti-abortion activists built media-savvy lobby groups, utilised technology such as sonograms to promote their arguments and set a goal to get their own justices on the Supreme Court.
In 2016 Donald Trump - who had never opposed abortion before running for president - courted Evangelical leaders and began to condemn abortion and say Roe should be overturned.
Mr Trump chose for his vice president Mike Pence, an Evangelical himself who as Indiana governor set tough restrictions on abortion.
Throughout his presidency, Mr Trump later repaid the religious right's support by naming three conservative justices to the Supreme Court, tilting the bench in their favour in a majority of 6-3.
What happens now?
Overturning Roe curbs access to abortions in many areas across the country, leaving states to set their own restrictions if they so choose.
In at least 13 states, abortion is illegal under "trigger bans" that are either immediate or come to effect after around 30 days from the ruling has been handed down.
These states have already enacted restrictions on abortion, led by a ban in Texas after about six weeks of pregnancy described as the "heartbeat bill". Kentucky, Georgia and Arizona all have passed slightly more lenient curbs, allowing abortion until 15 weeks. Idaho is likely to allow abortion until 24 weeks.
Other states have abortion bans on the books from before the 1973 landmark ruling.
Oklahoma's total ban has been enacted immediately. It outlaws all terminations except when the mother's life is in danger. This is also the case for Utah, Alabama, Missouri and Louisiana.
Planned Parenthood, the leading US reproductive rights group, has said it would still be legal for Americans to travel interstate to receive an abortion.
Abortion sanctuaries in the US
While it's believed up to 26 states in the US will impose some restrictions or another on abortion, others have rallied together to provide added assistance in anticipation of increased demand from around the country.
It's expected progressives state such as Illinois, which is surrounded by states that restrict abortion, can expect to see a huge influx of patients.
The Democratic governors of California, Oregon and Washington issued a joint video message on Friday declaring that the West Coast will "remain a place where reproductive health care will be accessible and protected."
On the other side of the country, New York governor Kathy Hochul said the northeast state "will always be a safe harbour for those seeking access to abortion care."
She announced a new advertising campaign to inform Americans that they can receive abortions while in her state.
"Everyone who passes through our subways, bus terminals, airports, and shopping centres will know that abortion remains safe, legal, and accessible in New York state," she tweeted.
What could Congress do?
US President Joe Biden lamented the decision struck down by the Supreme Court, but he alone cannot change the law.
"The only way to ensure we can secure a woman's right to choose and the balance that existed is for Congress to restore the protections of Roe v Wade as federal law," he said. "No executive action from the president can do that."
US President Joe Biden said he will do everything in his power to assist women after the Supreme Court overturned Roe v. Wade. Source: AAP / AP / Andrew Harnik
The House has already passed a bill to do this but the Senate voted against it.
Mr Biden vowed to do "all in my power" to curb the impact of the court's ruling - citing for instance women's right to travel out of state to receive reproductive care, and access to abortion pills.
But he did not touch on calls for abortion clinics to be built on federal land in conservative states - or for reform of the Supreme Court.
What do Americans want?
Polling on abortion is split, generally showing around 25 per cent of Americans believe it should be legal in all cases, and another 25 per cent thinks it should be allowed in most.
About 25 per cent believe abortion should be illegal in most cases, and a smaller proportion - around 10 to 15 per cent - believe it should be illegal in all cases.
A CNN poll in January found that 69 per cent of respondents were against doing away with Roe while 30 per cent were in favour.
