A US federal judge on Wednesday temporarily blocked a law that bans most abortions in Texas as part of a conservative drive to deny access to the procedure.

The statute, which went into force on September 1, prohibits abortions as soon as a heartbeat is detectable, usually at around six weeks of pregnancy, before many women even know they are pregnant. There are no exceptions for cases of incest or rape.

US District Judge Robert Pitman in Austin granted the request from President Joe Biden's administration to block enforcement of the law pending further litigation, on grounds it violates the US constitution. Texas can appeal.

In his 113-page ruling, Pitman said Texas officials had created an "unprecedented and aggressive scheme to deprive its citizens of a significant and well-established constitutional right."

Protesters take part in the Women's March and Rally for Abortion Justice at the State Capitol in Austin, Texas on October 2, 2021
Protesters take part in the Women's March and Rally for Abortion Justice at the State Capitol in Austin, Texas on October 2, 2021 AFP / Sergio FLORES

"From the moment SB 8 went into effect, women have been unlawfully prevented from exercising control over their lives in ways that are protected by the Constitution," Pitman said, using the abbreviation for Senate Bill 8, the law's official name.

"This Court will not sanction one more day of this offensive deprivation of such an important right."

In recent years, similar laws have been passed in other states but were struck down because they violated US Supreme Court precedent from Roe v. Wade, the 1973 ruling that guaranteed a woman's right to an abortion until the fetus is viable outside the womb, at around 22 weeks of pregnancy.

The Texas law, which thus far is the most restrictive in the country, is unique in that it empowers anyone to file a lawsuit against a person who has assisted in an abortion. They can be rewarded with $10,000 for initiating cases that lead to prosecution, prompting charges that the law encourages Texans to act as vigilantes.

As Texas can still appeal Pitman's order, the case may end up in front of the Supreme Court.

Protesters march past the US Capitol as they take part in the Women's March and Rally for Abortion Justice in Washington, DC, on October 2, 2021
Protesters march past the US Capitol as they take part in the Women's March and Rally for Abortion Justice in Washington, DC, on October 2, 2021 AFP / ANDREW CABALLERO-REYNOLDS

The White House welcomed the ruling as "an important step forward toward restoring the constitutional rights of women across the state of Texas."

But the right to abortion remains under attack there and in other states, said spokeswoman Jen Psaki, so Biden supports codifying Roe v. Wade into law and "will continue to stand side-by-side with women across the country to protect their constitutional rights."

The nine-justice Supreme Court, with its clear conservative majority, cited procedural issues when it decided last month against intervening to block the Texas law, as pro-choice advocates had requested. It did not rule on the merits of the case.

Demonstrators rally against anti-abortion and voter suppression laws at the Texas state capitol in Austin, on October 2, 2021
Demonstrators rally against anti-abortion and voter suppression laws at the Texas state capitol in Austin, on October 2, 2021 GETTY IMAGES NORTH AMERICA / Montinique Monroe

The court had already agreed to review a restrictive Mississippi law that could also provide an opportunity to overturn Roe v. Wade.

The justices' declining to block the Texas law prompted the Biden administration to enter the fray, citing its interest in upholding Americans' constitutional rights.

In court arguments Friday, the US government described the ban as "a truly extraordinary law designed to outflank the federal government and to violate the constitution."

Attorney William Thompson of the Texas Attorney General's Office accused the government of "inflammatory rhetoric" and insisted the law respects Supreme Court precedent.

But Judge Pitman retorted: "If the state's so confident in the constitutionality of the limitations on a woman's access to abortion, then why did it go to such great lengths to create this very unusual private cause of action?" He was referring to the clause allowing everyday people to file lawsuits over abortions in Texas.

Tens of thousands of women took to the streets across the United States at the weekend in protests aimed at countering the conservative drive to restrict abortion access.

Pro-abortion advocates have called on Congress to enshrine the right to abortion in federal law, so as to protect it from any possible reversal by the Supreme Court.

A bill to that effect was adopted two weeks ago in the House of Representatives, which is controlled by Democrats, but has no chance of passing the Senate where Republicans have enough votes to block it.

Then-president Donald Trump's appointment of three conservative justices to the Supreme Court emboldened local conservative elected officials across the country to embark on an anti-abortion offensive.

If the high court were to overturn Roe v. Wade, every state would be free to ban or allow abortions.

That would mean 36 million women in 26 states -- nearly half of American women of reproductive age -- would likely lose the legal right to an abortion, according to a Planned Parenthood report.