Attorneys for Donald Trump on Thursday took their fight over the president’s tax returns to the Supreme Court, bucking more than four decades of transparency norms in a case that could determine if the nation’s highest officeholder has blanket criminal immunity while in office.

If the Supreme Court considers the case, it could pave the way for another fight over the reach of presidential powers amid a historic impeachment inquiry in the House of Representatives.

If the court declines to hear the case, it would force Trump to turn his tax returns over, which he promised to do previously. Attorney Jay Sekulow put the onus on the court to hear the case, and it takes four ‘yes’ votes from the nine justices to hear a case. Conservatives hold a 5-4 majority on the court, but this case could easily go either way because it would set a major precedent for presidential authority in the years to come.

“Every time a President has asked the Court to review an unprecedented use of legal process against the occupant of the office, it has done so,” Sekulow said.

A federal appeals court ruled this month that Trump’s accounting firm, Mazars USA, must hand over eight years worth of Trump’s corporate and federal tax returns to the Manhattan District Attorney’s office in response to a subpoena.

Sekulow said it was “the first time in our nation’s history” that a local DA had launched a criminal investigation into the president, and he urged the court to “decide the important and unsettled issue this dispute raises.”

The question is “whether the District Attorney’s issuance of criminal process demanding the President’s records violates the immunity that he holds under Article II and the Supremacy Clause of the Constitution.”

Manhattan DA Cyrus Vance Jr. says the investigation is over potential violations of state law. His office is investigating hush-money payments paid to Stephanie Clifford, aka Stormy Daniels, and former Playboy model Karen McDougal in the lead-up to the 2016 election.

Then-Trump lawyer Michael Cohen paid Clifford $130,000 to keep quiet about an alleged affair, and Trump ally David Pecker’s National Enquirer paid McDougal $150,000 to keep quiet about another alleged affair. Trump of course has denied both affairs.

Cohen himself is now serving a three-year prison term over the ordeal for campaign finance violations, which he said were done to protect Trump from the damage the stories would have done to his campaign in the final stretch before the election. Trump’s company and Trump himself reimbursed Cohen the money.

Trump’s legal team has basically said that while he is in office, he is immune from any criminal prosecution and investigation, which judges in previous courts scoffed at, essentially saying a president isn’t a king with blanket authority to do as he pleases. Trump’s lawyers went so far as to claim he could shoot someone on Fifth Avenue in New York City and not face prosecution until he left office.

A different case brought by House Democrats over the tax returns is pending in Washington. On Wednesday, a D.C. Court of Appeals ruled it would let a previous ruling that the documents had to be turned over stand, and Trump’s lawyers vowed to bring that case to the Supreme Court as well.

Trump is the first president in more than 40 years who has opted not to release his tax returns.

Editor’s note: Do you think the president should hand over his tax returns, as has been customary for the sake of transparency for more than four decades? Why or why not? Is it fair to say if he has nothing to hide, then why not release them? Share your thoughts below.