President Trump asked the Supreme Court on Thursday to keep his tax returns out of the hands of Manhattan District Attorney Cyrus Vance.

Through his personal attorneys, Trump asks the high court to block a state grand jury subpoena, asserting his immunity from any kind of criminal investigation while in office.

The move sets up a historic battle over the extent of presidential power and the rule of law.

“For the first time in our nation’s history, a state or local prosecutor has launched a criminal investigation of the President of the United States and subjected him to coercive criminal process,” they write in the petition for a writ of certiorari.

The Second Circuit Court of Appeals struck down Trump’s bid to contest the subpoena, issued to longtime Trump accountant Mazars USA LLP in late August as part of an investigation into whether the Trump Organization illegally paid hush money to a porn star and former Playboy model who both alleged they had affairs with with the President.

The timing of the case could mean that the Supreme Court may issue a ruling on a major, fundamental case during the 2020 election campaign. Trump is fighting to prevent prosecutors from accessing financial records that could show details of payoffs to the two women.

The President’s personal attorney William Consovoy argued at that hearing that if Trump were to shoot someone in the middle of Fifth Avenue, he could not be investigated or arrested.

“That the Constitution would empower thousands of state and local prosecutors to embroil the President in criminal proceedings is unimaginable,” the petition to the Supreme Court reads.

Trump argues that the same standing Justice Department policy which forbids a federal criminal prosecution of a sitting president should apply to any criminal investigation at any level as well.

“Allowing the sitting President to be targeted for criminal investigation—and to be subpoenaed on that basis—would, like an indictment itself, distract him from the numerous and important duties of his office, intrude on and impair Executive Branch operations, and stigmatize the presidency,” the filing reads.

Trump also accuses Vance of “invad[ing] Congress’s impeachment authority” by conducting his investigation.

Read the petition here: