U.S. Supreme Court: A check or an enabler of second Trump presidency?

Donald Trump returns to the White House shielded with presidential immunity by the Supreme Court and with the prospect of cementing a conservative majority on the bench for at least a generation.

The Republican President-elect appointed three right-wing justices to the top court during his first term and may have the opportunity to name more during his second stint in the Oval Office.

Archconservatives Clarence Thomas, 76, and Samuel Alito, 74, who wrote the opinion overturning the nationwide right to abortion, are the two oldest justices on the court and they could choose to step down knowing their replacements would be nominated by Trump.

"It certainly presents the opportunity for them to retire with some assurance that their successor would continue their philosophy," said Christopher Peters, a law professor at the University of Akron. "And I certainly wouldn't be surprised if that happened."

Steven Schwinn, a law professor at the University of Illinois Chicago, said if Thomas or Alito have any inclination to quit he expects it to happen "fairly quickly" -- before the 2026 midterm elections, when Republicans could potentially lose control of the Senate.

Supreme Court justices are appointed by the president for life but are subject to confirmation by the Senate.

Trump, the only former US president to be convicted of a crime -- falsifying business records to cover up a hush money payment to a porn star -- will take office in January emboldened by the top court's ruling in July that an ex-president has broad immunity from criminal prosecution, Schwinn said.

Trump was charged by Special Counsel Jack Smith with conspiring to overturn the results of the 2020 election but a trial was delayed by appeals that eventually landed in the Supreme Court, where conservatives enjoy a 6-3 majority.

In an opinion penned by Chief Justice John Roberts, the court ruled that a former president has broad immunity from prosecution for official acts taken while in office, but can be pursued for unofficial acts.

Smith, the special counsel, is winding down the election interference case against Trump in light of the long-standing Justice Department policy that a sitting US president cannot be indicted or criminally prosecuted.

- 'King above the law' -

Schwinn said the immunity ruling "not only allows, but affirmatively invites, a president to engage in illegal behavior and provides a kind of roadmap for doing that while also immunizing themselves.

"And then the question is, 'Is a particular president willing to abuse that power or not?'" he said. "And you know, for my money, I guess a President Trump seems more likely to do that."

Justice Sonia Sotomayor, one of the three liberals on the court, warned in her blistering dissent to the immunity ruling that it makes the president a "king above the law."

Steve Vladeck, a law professor at Georgetown University, noted that the Supreme Court did check Trump on a number of occasions during his first term in the White House.

The court initially blocked his Muslim travel ban, protected the young undocumented immigrants known as "Dreamers," and declined to be dragged into lawsuits filed by Trump surrogates falsely claiming he had won the 2020 election.

With Republicans controlling both chambers of Congress this time, the Supreme Court will be "the last institution standing between Mr Trump and whatever he wants to do," Vladeck said in a New York Times essay.

But the court, Vladeck noted, has its own problems with approval ratings at near record lows and perceived ethics questions surrounding luxury vacations taken by Thomas and Alito that were paid for by powerful Republican billionaires.

"Without that public support, what would happen if Mr Trump simply ignored a decision by the nation's highest court that he doesn't like?" Vladeck asked.

"If the court rules against Mr Trump and he tells the justices to pound sand, what will happen then?"