"Local authorities couldn't investigate? They couldn't do anything about it?" Chin asked, adding: "Nothing could be done? That's your position?"
"That is correct. That is correct," Consovoy said.
The panel did not immediately indicate when it would issue a ruling, but Judge Robert A. Katzmann, the appeals court's chief judge, signalled that he and the other judges understood both the gravity of the matter and that they were unlikely to have the final word.
"This case seems bound for the Supreme Court," Katzmann said early in the arguments, adding later, as the hearing wrapped up, "We have the feeling you may be seeing each other again in Washington."
A deal struck with the district attorney's office will allow the president time to seek a speedy review of the appellate ruling in the Supreme Court on the condition that he ask that the court hear the case in its current term, which ends in June.
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The district attorney, Cyrus R. Vance Jr., a Democrat, has agreed not to seek enforcement of the subpoena until the Supreme Court either refuses to hear Trump's case or issues an opinion, whichever comes first. Vance was present in the spectator section of the courtroom as the arguments took place.
The 2nd US Circuit Court of Appeals in Manhattan typically decides cases through three-judge panels. The panel members who heard the subpoena dispute were Katzmann, Judge Denny Chin and Judge Christopher F. Droney.
Katzmann was appointed to the appeals court by President Bill Clinton. Chin and Droney were appointed by President Barack Obama.
The appeal by Trump's lawyers came after a lower court judge ruled October 7 that the president's argument that he could not be investigated by a local prosecutor was "repugnant to the nation's governmental structure and constitutional values."
Vance's office in late August subpoenaed Trump's accounting firm, Mazars USA, for his personal and corporate tax returns dating to 2011.
The district attorney had been investigating whether any New York state laws were broken when Trump and his company, the Trump Organisation, reimbursed Michael Cohen, the president's former lawyer and fixer, for payments he made to pornographic film actress Stormy Daniels, who had said she had an affair with Trump. Trump has denied the affair.
Trump went into federal court last month, trying to block the district attorney's subpoena. The president argued that the Constitution prevented a sitting president from being "investigated, indicted or otherwise subjected to criminal process."
"The subpoena is a bad faith effort to harass the president by obtaining and exposing his confidential financial information, not a legitimate attempt to enforce New York law," the president's lawyers wrote.
After Judge Victor Marrero of US District Court in Manhattan, in a 75-page ruling, rejected Trump's broad argument, the president's lawyers appealed to the 2nd Circuit.
They contended that Trump's claim of absolute immunity was meritorious; they said the framers of the Constitution, recognising the need for a strong chief executive, created a process — impeachment — for investigating and removing a president in a manner that would "embody the will of the people."
"A lone county prosecutor cannot circumvent this arrangement," they said.
The Justice Department also weighed in, telling the appeals panel that the case raised "significant constitutional issues."
The government is not a party to the case but has the right to provide its views.
The Justice Department, led by William Barr, asked that the court stop the release of Trump's tax returns and reiterated its long-standing position that a sitting president may not be charged or prosecuted.
But the department appeared to leave open the door for Trump to be investigated by Vance's office.
The department argued that a local prosecutor had to meet a high legal bar before investigating a sitting president and that Vance should not be able to obtain the president's personal records "unless and until — at a minimum — the District Attorney is able to make the required showing of particularised need."
The department said the district attorney would have to show that the records it was seeking from Trump were central to the grand jury investigation, were not available elsewhere and were needed immediately, as opposed to after Trump leaves office.
Vance's office, citing Trump's arguments in the case, told the appeals court in a brief that Trump's "core position on every one of these matters is that the United States presidency places him beyond the reach of the law."
Written by: Benjamin Weiser and Azi Paybarah
© 2019 THE NEW YORK TIMES