MANHATTAN (CN) – The constitutional argument at the heart of President Donald Trump’s lawsuit last week seeking to quash a New York prosecutor’s subpoenas of his tax returns rested on an extraordinary assertion of executive power that would immunize him and his allies from the criminal process.

Such a position, Manhattan District Attorney Cyrus Vance told a federal judge on Monday, would “invent and enforce” a new concept of “tax return privilege” never imagined in law or historical precedent.

“Again, there is no ‘immunity from scrutiny’ of this sort in the law,” Vance’s assistant Carey Dunne wrote in a 20-page memo.

The prosecutors made a point to note that every U.S. president since Jimmy Carter voluntarily released his tax returns “before or upon taking office, which has never impeded a president’s ability to serve.”

Breaking from that tradition, Trump has fought every jurisdiction attempting to scrutinize his finances, including the Manhattan district attorney, House Oversight Committee, House Intelligence Committee, and attorneys general from Maryland and Washington. Trump has succeeded so far in putting those subpoenas on pause, even after initially losing federal court battles, by appealing every ruling against him.

In essence, Vance’s new legal briefs argue, Trump seeks a “blanket immunity from criminal prosecution” extending to “any routine, lawful grand jury request for information” related to his businesses, employees or himself before taking office. This shield also would supposedly apply to third parties.

“In other words, [Trump’s] position is that none of this conduct, unrelated to the office of the president, can be investigated while the president remains in office,” the memo states.

Trump’s legal team—comprised of attorneys Alan Futerfas, Marc Mukasey, Patrick Strawbridge, and William Convosoy—deployed a federalist argument against the county prosecutor, arguing that the search violated the supremacy clause of the Constitution.

Vance insists that the reverse is true, and federal courts should tread lightly in interfering with state investigations.

“There is an ongoing state proceeding; states unquestionably have an important interest in the enforcement of their grand jury subpoenas; and plaintiff can raise his constitutional claims in state court,” the memo states.

Though the details are shrouded in secrecy, Vance’s investigation is undoubtedly broad in scope, seeking eight years of Trump’s personal and corporate tax returns in connection with a criminal investigation into hush-money payments to adult film actress Stormy Daniels.

The Aug. 29 subpoena of Trump’s accounting firm Mazars sought a wide swath of files pertaining to Trump and more than 10 of his related entities dating back to Jan. 1, 2011.

Beyond such disclosures, Manhattan prosecutors have kept quiet about the targets of their investigation and the charges that they are seeking. A subsection of a newly filed court document describing the investigation is entirely redacted.

Despite Trump’s aggressive litigation posture now, Vance claims that the Trump Organization initially cooperated with a grand jury subpoena it received on Aug. 1. Prosecutors say that the company provided 3376 responsive pages, “but no tax records.”

Futerfas, one of Trump’s attorneys, did not immediately respond Monday to an email requesting comment.