Sonia Sotomayor, the liberal-leaning justice on the US supreme court, put it plainly. For almost three months, lawmakers in the Republican-controlled legislature of Texas had “substantially suspended a constitutional guarantee: a pregnant woman’s right to control her own body”.

“The court should have put an end to this madness months ago,” Sotomayor said.

But when the supreme court issued on Friday its majority opinion on SB8, the extreme Texas law that bans abortions effectively at six weeks, in blatant violation of the court’s own constitutional rulings, it still didn’t put an end to the madness.

It allowed the law, the most restrictive currently in force in the US, to remain in effect.

And by varying margins, the new conservative supermajority of the court, consolidated by Donald Trump’s appointment of three new rightwing justices, restricted the legal route by which abortion providers could challenge the law.

From now on the legal battle would have to be focused narrowly on just four state employees responsible for medical licensing in the state. Other Texas officials involved, notably the state’s attorney general Ken Paxton and clerks in state courts, would be let off the hook.

Even more provocatively, while the court sent the abortion fight back to a federal district court in Austin, it let the ban itself stand. That adds insult to injury given the supreme court’s much-criticised refusal to stay the ban at the start, not to mention the many weeks it has taken to hand down its decision.

Over those weeks, Texas women have paid a heavy price. “The court’s delay in allowing this case to proceed has had catastrophic consequences for women seeking to exercise their constitutional right to an abortion in Texas,” Sotomayor said in a powerful dissenting opinion.

In September alone, the first month of the ban, the number of legal abortions performed in Texas plummeted to about half the level a year ago. That was the largest recorded decline in the state’s recent history, with untold numbers of women forced to seek abortions out of state or carry unwanted pregnancies to term.

Sotomayor, who is emerging as a pivotal voice of resistance within the post-Trump court, was forthright in her choice of words. Her disagreement with the conservative justices went far beyond a “quibble” over which state officials abortion providers can sue, she said.

The question was: is the supreme court prepared to stand up in the name of constitutional rights to the cynical antics of ideologically driven Republicans in states such as Texas?

“The choice to shrink from Texas’s challenge to federal supremacy will have far-reaching repercussions,” Sotomayor warned. “I doubt the court, let alone the country, is prepared for them.”

Nobody can doubt that SB 8 is a flagrant violation of the constitutional right to an abortion enshrined in the 1973 landmark ruling Roe v Wade. While Roe sets the bar of fetal viability at about 24 weeks, Texas now puts it at the point of earliest cardiac activity, around six weeks – before many women even know they are pregnant.

Neil Gorsuch, one of the three Trump appointees, who wrote Friday’s majority opinion, said that the issue of the constitutional right to an abortion was not under consideration in this case. The matter at hand in the Texas law was whether abortion providers could press on with their challenge to the ban by suing specific state officials.

That will do little to assuage the jitters of 80% of Americans who think that abortions should be legal in all or certain circumstances. In a separate case before the supreme court based on a new Mississippi ban at 15 weeks, which is now blocked by a lower court, Roe v Wade is very much up for grabs, and the signs are ominous.

In oral arguments in the Mississippi case less than two weeks ago, several of the conservative justices indicated they were willing to sharply restrict or even overturn the right to an abortion despite its rock-steady standing as a pillar of constitutional law for almost 50 years.

Nor does Gorsuch’s protestation that Friday’s case was merely focused on procedural matters offer much comfort. SB 8 was devised by Texas Republicans as a juridical trick to skirt around constitutional protections by making it more difficult for abortion providers to challenge the law in federal court.

At the heart of the legislation is a ruse designed to make a mockery of federal oversight. Enforcement of the abortion ban is transferred from state officials who are vulnerable to federal challenge to private individuals, armed with financial inducements of up to $10,000 to cover legal fees.

“SB 8 is structured to thwart review and result in ‘a denial of any hearing’,” Sotomayor decried. “The events of the last three months have shown that the law has succeeded in its endeavor.”

That is why the vote of the court’s new post-Trump majority to issue such a narrow opinion over SB 8 is more than a “quibble”. The highest court in the nation has been defied by a group of extremist Republicans openly flouting the court’s own rulings.

In response, the conservative majority emboldened by Trump has opted not to insist on respect for the constitutional law of the land, but instead to blithely play along.

As Sotomayor put it: “By so doing, the court leaves all manner of constitutional rights more vulnerable than ever before, to the great detriment of our constitution and our republic.”

Perhaps most tellingly, the idea of appeasing Texas Republicans in their attempt to undermine the supreme court’s own precedents proved too much even for John Roberts, the chief justice.

In important aspects of Friday’s decision, he broke with his five fellow conservative justices and sided pointedly with Sotomayor and the liberal minority.

“The clear purpose and actual effect of SB 8 has been to nullify this court’s rulings,” Roberts said, in words which may reverberate down the years.

“The role of the supreme court in our constitutional system is at stake.”