The Supreme Court of the United States ruled to not block a new law in Texas that bans abortions for most women.
The so-called Heartbeat Act bans terminations after the detection of what anti-abortion campaigners call a foetal heartbeat – a point when many women do not know they are pregnant.
The law gives any individual the right to sue doctors who perform an abortion past the six-week point.
Rights groups had asked for an injunction to prevent its enforcement.
But in a late night vote, the Supreme Court justices ruled 5-4 against granting this.
The court’s majority said their decision was not based on any conclusion about whether the Texas law was constitutional or not, and that the door remained open for legal challenges.
All three of former President Donald Trump’s Supreme Court appointees voted against blocking the ban.
One of the court’s six conservatives, Chief Justice John Roberts, joined the three liberal justices in dissent.
Liberal Justice Sonia Sotomayor called the court’s order “stunning”.
“Presented with an application to enjoin a flagrantly unconstitutional law engineered to prohibit women from exercising their constitutional rights and evade judicial scrutiny, a majority of justices have opted to bury their heads in the sand,” she said.
President Joe Biden has condemned the law, which came into effect on Wednesday. He called it “extreme” and warned that it would “significantly impair” women’s access to healthcare.
Rights groups including Planned Parenthood and the American Civil Liberties Union (ACLU), who had requested that the Supreme Court block the legislation, say they will not give up the fight.
Texas’ Republican Governor Greg Abbott, who signed the Heartbeat Act into law, said the state would “always defend the right to life”.
“No freedom is more precious than life itself,” he tweeted.