The case is one of several pending legal disputes over access to Trump's financial records, and it appears on track to become the first to reach the Supreme Court if the judges accept the case. It's also part of a broader suite of legal cases that could determine whether prosecutors and congressional investigators will get access to Trump-related personal records, government documents and witness testimony. Thus far, Trump and the Department of Justice have faced a few legal setbacks at the lower court level, but many of these cases could take months to sort out as they make their way to the Supreme Court level.

On Monday, the appeals court dismissed concerns Trump’s lawyers raised about the potential state prosecution of a president while in office. Second Circuit Chief Judge Robert Katzmann said the current case did not present that question and he stressed that the records don’t pertain to Trump’s official duties.

“After reviewing historical and legal precedent, we conclude only that presidential immunity does not bar the enforcement of a state grand jury subpoena directing a third party to produce non-privileged material, even when the subject matter under investigation pertains to the President,” Katzmann wrote, in an opinion joined by Judges Denny Chin and Christopher Droney.

The appeals court’s opinion noted that during the Watergate scandal, the Supreme Court ruled that President Richard Nixon’s Oval Office tapes and documents had to be turned over for a federal trial of former Nixon aides. Katzmann said the Trump lawyers’ arguments were less weighty than the ones the justices rejected in 1974.

“The President has not persuasively explained why, if executive privilege did not preclude enforcement of the subpoena issued in Nixon, the Mazars subpoena must be enjoined despite seeking no privileged information and bearing no relation to the President’s performance of his official functions,” Katzmann wrote.

“We are not faced, in this case, with the President’s arrest or imprisonment, or with an order compelling him to attend court at a particular time or place, or, indeed, with an order that compels the President himself to do anything," the judge added. "The subpoena at issue is directed not to the President, but to his accountants; compliance does not require the President to do anything at all."

Katzmann also emphasized the sweeping nature of the claim by Trump’s lawyers — that records pertaining to him cannot be subpoenaed as long as he is president, even if the investigation focuses on individuals beyond Trump himself.

“The subpoena seeks only the President’s private tax returns and financial information relating to the businesses he owns in his capacity as a private citizen. These documents do not implicate, in any way, the performance of his official duties,” Katzmann added.

Trump’s legal team suggested Monday that the opinion threatens the independence and powers of all future presidents.

“The issue raised in this case goes to the heart of our Republic,” Sekulow said in a statement vowing an appeal to the Supreme Court. “The constitutional issues are significant.”

Katzmann also appeared to tweak Trump for departing from the tradition in recent decades of presidents making their tax returns public.

“We note that the past six presidents, dating back to President Carter, all voluntarily released their tax returns to the public. While we do not place dispositive weight on this fact, it reinforces our conclusion that the disclosure of personal financial information, standing alone, is unlikely to impair the President in performing the duties of his office,” the appeals court observed in a footnote.

All three judges who ruled on the appeal are Democratic appointees. Katzmann was appointed by President Bill Clinton. Chin and Droney were appointed by President Barack Obama.

Separately, Trump has filed two other lawsuits to prevent banks and the same accounting firm, Mazars, from responding to House subpoenas for his financial information. Last month, a three-judge panel of the D.C. Circuit rejected Trump’s challenge to the congressional subpoena to Mazars, but Trump’s attorneys have asked the full bench of that court to rehear the appeal.

The House Ways and Means Committee is also suing to force the Treasury Department to comply with the panel’s request for Trump’s tax returns and related records. No ruling has been issued yet in that case.

Darren Samuelsohn contributed to this report.