A leaked first draft of the majority opinion in the case, authenticated Tuesday by the Supreme Court, suggests that a majority of justices are poised to toss out Roe. The draft's provocative rhetoric also is generating concern that LGTBQ advances and other matters based on the right to privacy could be vulnerable in a newly hostile political environment.

"This is about a lot more than abortion," President Joe Biden warned Wednesday, saying the court's draft opinion could jeopardise same-sex marriage, access to contraception and LGBTQ rights.

"What are the next things that are going to be attacked? Because this MAGA crowd is really the most extreme political organisation that's existed in recent American history," Biden said.

Court opinions can change in ways big and small throughout the drafting process. So while the eventual ruling in the abortion case appears all but assured, the written rationale - and its implications - may still be a hotly debated subject inside the court's private chambers.

The draft's potentially sweeping impact could be tempered by the other justices, or it could emerge largely unchanged - with what advocates and Biden say could bring even more severe consequences.

The draft opinion, written by Justice Samuel Alito, a member of the court's 6-3 conservative majority, argues that unenumerated constitutional rights - those not explicitly mentioned in the document - must be "deeply rooted in the nation's history and traditions." And it says abortion doesn't meet that standard.

Biden and others are sounding alarms that the same logic could be used to toss out other protections.

The President said he believed the conservative justices on today's court would, like failed Supreme Court nominee Robert Bork in 1987, disagree with the court's ruling in Griswold v. Connecticut, which said that a right to privacy exists that bars states from interfering in married couples' right to buy and use contraceptives.

Cases like Lawrence v. Texas, which struck down sodomy laws criminalising same-sex intimacy, and Obergefell v. Hodges, which legalised gay marriage, are based at least in part on that same right to privacy.

Alito, in the draft opinion, explicitly states that the court is only targeting the right to abortion, not those other matters.

"We emphasise that our decision concerns the constitutional right to abortion and no other right," the draft states. "Nothing in this opinion should be understood to cast doubt on precedents that do not concern abortion."

Obergefell is different from Roe in that hundreds of thousands of same-sex couples have relied on it to wed and created legal bonds, like shared property, inheritance rights and "settled expectations about the future," said Teresa Collett, a professor at the University of St. Thomas School of Law and director of its Prolife Centre.

Courts are usually loath to undo that kind of precedent. It stands in contrast to abortion, which is usually "a response to unplanned circumstances," Collett said.

Obergefell, moreover, relies on the Constitution's Equal Protection Clause as well as the right to privacy.

The current Supreme Court abortion case specifically concerns a Mississippi law that bans abortion after 15 weeks - before the "viability" standard set in the 1992 case Planned Parenthood v. Casey, which itself moved beyond Roe's initial trimester framework for regulating abortion.

At arguments in December, all six conservative justices signaled they would uphold the Mississippi law, and five asked questions suggesting they supported overturning the right to abortion nationwide, leaving the issue up to individual states.

Only Chief Justice John Roberts seemed prepared to take the smaller step of upholding the 15-week ban, in essence overturning the court's ruling in Casey, while leaving in place the right to an abortion in Roe.

Until now, the court has allowed states to regulate but not ban abortion before the point of viability, around 24 weeks. The court's three liberal justices appeared certain to be in dissent.

READ MORE:

Still, the language and tone Alito uses overall could encourage more challenges, said Jason Pierceson, professor of political science at the University of Illinois, Springfield. "If the right to privacy is deconstructed or is hollowed out, or is minimised, then those cases in particular have less standing," Pierceson said.

A challenge to same-sex marriage could come before the High Court on religious liberty grounds, for example, such as someone arguing their religious faith prevents them from recognising same-sex marriage. Cases along those lines have been mostly about exceptions to anti-discrimination laws so far, Pierceson said, "but one could see potentially a broadening of the argument to the fact that maybe same-sex marriage laws are unconstitutional in the first place."

LGBTQ rights have made rapid progress over the past decade, and public opinion overall has become much more supportive. But especially over the past year there has been a wave of bills in state legislatures aimed at transgender youth sports and healthcare, as well as talking about LGBTQ issues in certain classrooms. Backers of those bills generally argue they're needed to protect kids and the rights of parents.

Against that backdrop, the draft opinion, if finalised, could "send up a flare" to conservative activists, said Sharon McGowan, legal director at Lambda Legal.

"Overturning Roe will be most dangerous because of the signal it will send lower courts to disregard all the other precedents that exist," she said.

"It's starting with abortion. It's not going to end with abortion," said Mini Timmaraju, the president of NARAL Pro-Choice America. "So everyone needs to be very vigilant."

Critics could also take a page from the anti-abortion playbook, which involved multiple measures over the decades that tackled the issue from different angles, imposed limits rather than sweeping prohibitions and employed unusual strategies like the civil-enforcement mechanism that's already essentially allowed Texas to ban abortion, said Alison Gash, a professor at the University of Oregon.

"It opens the door for all sorts of stuff that I think we're probably going to see now that we've got a court that seems willing to support that kind of creativity," she said. "It's all speculation, but it seems perfectly plausible for us to see Republican experimentation on a whole bunch of policies that could be affected by this."

Donna Lieberman, executive director of the New York Civil Liberties Union, said that "what comes through loud and clear in the draft" is that the agenda "is not just to get rid of abortion but to ban contraception, to eliminate all the important progress that we've made about LGBTQ rights, about the rights of trans children, and also about racial equality."