During oral arguments in three cases Tuesday, the justices will explore Trump's claim that he cannot be subjected to subpoenas or any criminal investigative process, by virtue of the demands of the presidency.
The assertion of expansive presidential power comes as Trump faces an array of mounting requests for his personal and business financial records. His efforts to challenge the subpoenas in federal courts have, so far, been unsuccessful at every level.
"These are critical cases that are going to decide whether or not a president, in office, has presidential immunity for the duration of the time that he is sitting in office," said Claire Finkelstein, a criminal law expert at the University of Pennsylvania Law School and director of its Center for Ethics and the Rule of Law.
"It would literally put the president above the law if the Supreme Court sides with the president's lawyers in this case," Finkelstein said.
The outcome will also determine whether Trump -- the only modern American president to have not publicly released tax returns or divest from major business interests while in office -- has to share more personal financial information with voters before the November election.
Three Democratic-led House committees and Manhattan District Attorney Cyrus Vance are seeking multiple years of documents as part of their respective investigations into potential wrongdoing by Trump prior to his presidency. The subpoenas are addressed to Trump's personal accounting firm, Mazars USA, and three financial institutions used by him and his business. Trump intervened to block the third parties from complying.
"These subpoenas are all expansive, burdensome, and unfocused fishing expeditions. They are inappropriate and should be invalidated," Trump's personal attorneys argued in court briefs.
The Trump legal team further claimed the requests are politically-motivated, illegitimate and a distraction from the important duties of presidential office. The Justice Department has filed an amicus brief siding with the president.
"The president cannot effectively discharge those duties if any and every prosecutor in this country may target him with criminal process," the Trump lawyers added.
Vance, a Democrat, has said he's seeking the records for an ongoing criminal probe into possible violations of state financial laws by Trump and the Trump Organization. The lawmakers say the information they seek is critical to drafting of federal ethics and anti-corruption legislation involving presidents.
"The mere risk of interference with official functions does not afford a president categorical immunity against subpoenas for documents concerning private conduct," Vance wrote in his brief. "Presidents throughout history have been subject to judicial process in appropriate circumstances."
In 1974, the Supreme Court ruled unanimously that President Richard Nixon had to obey a subpoena from the Watergate special prosecutor and turn over tapes and documents, limiting "executive privilege" protections for certain presidential communications.
Twenty-three years later, the court rejected President Bill Clinton's claims of broad immunity from litigation while in office, requiring him to participate in a videotaped deposition in a civil case involving Paula Jones, a former Arkansas state employee who accused Clinton of sexual harassment.
"Under its own precedent, it is hard to see how the Supreme Court can allow Trump to block congressional or prosecutorial subpoenas to third parties, like banks and accounting firms," said Harry Sandick, a former Assistant U.S. Attorney for the Southern District of New York.
"Trump literally would have to do nothing (to comply), since the subpoenas were served on banks and accounting firms, not on him personally," added Sandick. "These subpoenas have nothing to do with the president acting as president, but instead concern the president acting as a private citizen."
The Supreme Court arguments will take place via teleconference and will be livestreamed to the public in a groundbreaking new arrangement prompted by the coronavirus pandemic. Trump will be the first sitting president who is party to a case before the court and is able to potentially respond in real-time on Twitter.
"I can only imagine the president's lawyers are going to make every effort to steal his telephone," said Tom Goldstein, a veteran Supreme Court litigator and founder of SCOTUSblog. "The president is a very busy guy, obviously, but the oral argument is going to be extremely tempting."
The White House could not say whether Trump planned to tune in to the audio-only session.
If lower court decisions are upheld in any of the cases, Trump likely would have to turn over at least some of his financial records just a few months before voters cast ballots in the November presidential election.
"What it would say is that this president is not different from any other president, that all presidents have to comply with the rule of law and with court proceedings," said Finkelstein.
There is also the chance the court offers a split decision in the cases, or sides with Trump across the board.
"They're probably pretty happy with the lower court reasoning in the cases," Neal Katyal, former solicitor general during the Obama administration, speculated of the justices in public remarks late last year.
Lower court rulings at both the district and appellate levels have upheld the subpoenas as serving legitimate purposes and not imposing undue burdens on the executive branch, since they do not involve official communications or presidential involvement.
Paul Clement, former solicitor general during the George W. Bush administration, suggested he shares Katyal's view that the court is likely to agree.
"I think if you look at the court's precedents, you know, the president's argument is a tough one," Clement said. "Maybe 'an uphill one' would be the right way to describe it."
The justices are expected to release their opinion by the end of June.
This report was featured in the Tuesday, May 12, 2020, episode of “Start Here,” ABC News’ daily news podcast.
"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.