Now Congress faces a very hard question: Subpoena President Donald Trump’s translator, or not?

On Saturday, The Washington Post’s Greg Miller reported new details of the extreme things done by Trump to conceal his talks with Russian President Vladimir Putin from even the senior-most members of Trump’s own administration. Trump even reportedly seized the interpreter’s notes after one of his meetings, the Trump-Putin sit-down at the Hamburg G20 meeting in July 2017. Even more disturbingly, Trump and Putin met privately a second time at Hamburg—with no American present. In an act of astonishing recklessness, Trump relied entirely on the Russian interpreter, preventing any U.S. record-keeping at all.

All this would be unusual enough for any president. It is more than suspicious for a president being formally investigated by the FBI as a possible Russian-intelligence asset.

Read: The strange, high-pressure work of presidential interpreters

Concern focuses most on Trump’s meetings with Putin at the Helsinki summit in July 2018. The Russian president, and the American president helped into office by the Russian president, met for two hours with no aides. No agenda was published before the meeting, no communiqué issued afterward. The Russian side later claimed that a number of agreements had been reached at the summit. Nobody on the American side seemed to know whether this was true. At a press conference four days after the meeting, Director of National Intelligence Dan Coats said, “I’m not in a position to either understand fully or talk about what happened in Helsinki.”

There’s only one American who does know: Marina Gross, the professional interpreter who assisted Trump.

Should she be asked? It’s a tough, tough, tough question.

Arguments against:

A friend who holds a senior foreign-policy position in an EU government was absolutely horrified at the prospect of a subpoena for Gross. No admirer of Trump’s, this person felt such a subpoena would create a new precedent that would shadow all future confidential presidential conversations with non-English-speaking heads of government, allied as well as adversarial.

The Trump administration would surely raise an executive-privilege objection. In the 1974 case U.S. v. Nixon, the Supreme Court rejected an absolute claim of internal privilege within the executive branch. But it acknowledged “the valid need for protection of communications between high Government officials and those who advise and assist them in the performance of their manifold duties.” The court stressed that this privilege was at its strongest in military and diplomatic affairs, which would presumably describe the Helsinki meeting.

There is a nontrivial possibility that Gross might refuse to testify. Interpreters have a strong professional code of confidentiality. This code is not recognized in law, but like a newspaper reporter protecting his or her sources, Gross might feel honor-bound to uphold the code anyway—risking a contempt citation or even jail. Should she be put in that position?

Against those arguments is this fact: We are facing very possibly the worst scandal in the history of the U.S. government. Previous high-profile cases of disloyalty to the United States—Julius and Ethel Rosenberg’s betrayal of atomic secrets to the U.S.S.R.; Secretary of War John B. Floyd’s allowing federal arsenals to fall into secessionist hands in 1861—did not involve presidents. Previous presidential scandals did not involve allegations of disloyalty.

Read: The dueling narratives on Trump and Russia

Is the president of the United States a Russian asset? Is he subject to Russian blackmail? Is he at this hour conniving with the Russian president against the interests of the United States? These are haunting questions, and Trump’s own determination to defy normal presidential operating procedures to keep secret his private conversations with Putin only lends credibility to the worst suspicions.

I wrote in my book Trumpocracy abo ut the “autoimmune disorders” triggered by this most corrupt, most authoritarian, and perhaps most compromised of all presidencies. Trump’s breaches of norms force other agencies of government to breach norms in reply, in order to protect supreme public interests threatened by Trump. These norm-breaches by the other agencies do genuine harm, just as the aggressive autoimmune responses of the human body do real harm. But the alternative—suppressing all immune responses—is to allow the infection to fester and eventually destroy the host it occupies.

The scandal of the Trump presidency leaves Americans only bad choices. Powers and privileges essential to the functioning of an honest and patriotic presidency are called into question by this dishonest and unpatriotic presidency. Succeeding presidents and Congresses will have to find a way to restore or replace busted norms with new ones—but pretending now that the old rules can function as intended is not only delusive, but dangerous.

Subpoena the interpreter now; write a new law formalizing the confidentiality of interpretation later.