By Nadine Yousif & Robin Levinson-King

BBC News

The US Supreme Court has extended until Friday a temporary block on limits to access of a popular abortion pill.

A Texas judge suspended approval of abortion drug mifepristone on 7 April, questioning its safety.

Parts of that decision were upheld on appeal, prompting the Biden administration to make an emergency request to the Supreme Court.

It's the most significant such case since the Supreme Court last year ended the nationwide right to abortion.

The pill - used in more than half of abortions in the US - was first approved by the Food and Drug Administration (FDA) more than two decades ago. Here's how we got here.

What has happened so far?

Earlier this month, a federal judge in Texas issued a preliminary injunction revoking the FDA's approval for the drug while he hears a lawsuit brought by a group of anti-abortion health professionals against the agency challenging the safety of mifepristone.

In the ruling, the Texas judge said the FDA had rushed the approval and did not properly consider side effects. The FDA and several leading health organisations, such as the American Medical Association, say the drug is safe and effective.

Minutes later, a federal judge in Washington state issued an opposing ruling, ordering the FDA to make no change to the drug's availability and preserving access to mifepristone in 17 US states.

With these two rulings directly contradicting each other, the government appealed to the New Orleans-based 5th Circuit Court of Appeals.

It also asked for the court to put the Texas order on hold while the appeal was heard, keeping mifepristone available.

The appeals court agreed to keep the drug on the market - but with additional restrictions.

What is the Supreme Court ruling about?

Last week, the US justice department and Danco Laboratories, which manufactures the drug, called on the Supreme Court to intervene, asking it remove restrictions from the pill while the lower appeals court continues to review the case as a whole.

On Friday, US Supreme Court Justice Samuel Alito, who oversees emergency matters for 5th Circuit, ordered a temporary block on the restrictions until Wednesday evening, when it would issue a decision on whether to keep mifepristone on the market while the Texas ruling works its way through the appeals process.

But by late Wednesday afternoon, the Supreme Court extended this deadline until Friday at 23:59 EDT on Friday (04:59 BST on Saturday), keeping mifepristone on the market in interim without restrictions.

The court - which has a 6-3 conservative majority - did not offer an explanation as to why.

Could access to abortion pills change?

Access to the abortion pill mifepristone across the US will hinge on what the Supreme Court decides to do.

If it sides with the 5th Circuit Court of Appeals or issues no ruling by the end of Friday, mifepristone will remain available but conditions on its access will be imposed immediately.

These conditions include requiring that the drug be taken in the presence of a physician, that patients cannot receive the pill by post, and that the window for use of the pill shortens from up to 10 weeks of pregnancy to seven.

What might this all mean for other drugs?

Critics say that by overriding the FDA's approval, the court in Texas has usurped the federal health agency's remit to regulate food, medicine, and medical devices.

The Food, Drug, and Cosmetic Act of 1938 gives the FDA the authority to determine whether drugs are safe and effective, and typically, courts have deferred to the agency when it comes to scientific and medical decision-making.

Legal experts warn the ruling opens the door for challenges to other approved medicines in the US and could also stifle development of future drugs.

1. Glenn Cohen, a Harvard Law School professor, told BBC News the pharmaceutical industry could be wary of more legal challenges, particularly to treatments that have become political flashpoints in the US, like transgender medical treatment and Covid-19 vaccines.

"It's possible in any space, but … it's going to trickle down in some ways and play out to be the worst for drugs that are needed sometimes by discrete and insular minorities," Prof Cohen said.

• How safe is the abortion pill mifepristone?
• How 'judge shopping' led to abortion-drug showdown

What happens next?

The Supreme Court is only deciding whether to put on hold the Texas ruling revoking access to mifepristone. At the moment, it is not debating the case itself. That is currently being decided on by the 5th Circuit court, although it eventually could make its way to America's top court, too.

Earlier this week, the Alliance Defending Freedom, a conservative Christian legal advocacy group that filed the initial lawsuit against the FDA, submitted a brief to the Supreme Court asking it to let the restrictions on mifepristone go into effect.

Their request has been supported by 147 Republican lawmakers, who submitted their own brief to the court, calling the removal of conditions on access to the drug "a dangerous game with the health and safety of women and girls."

On the opposing side, a group of 253 Democratic lawmakers also weighed in, asking the Supreme Court to pause the original Texas ruling and leave mifepristone on the market as the case makes its way through the courts.

The Democrats argued the Texas ruling would restrict access to abortion nationwide.

Both briefs indicate that abortion remains a politicised debate in the US.