There is a substantial and impatient audience both within and outside Congress for Special Counsel Robert Mueller’s testimony on the Russia investigation. The House judiciary committee is negotiating for Mueller to appear, and while the Trump administration is busily objecting to other appearances, such as that of former White House Counsel Don McGahn, it seems prepared to relent in the case of Mueller. President Trump has tweeted out his unhappiness about a potential appearance by Mueller, but he also stated that the decision rests with Attorney General William Barr. And Barr recently declared that whether Mueller appears will be the special counsel’s “call.” In any event, there is now a settled expectation that the Russia investigation cannot come to a close until Congress has heard from Robert Mueller.

It turns out that, according to press reports, Mueller has his own reservations. The New York Times reports that the judiciary committee’s negotiations with Mueller have gone slowly. Moreover, “House aides involved in the report say they have gotten the sense that Mr. Mueller, and some of his aides, would rather let his written report speak for itself than push him into the partisan fray.” Under discussion between the special counsel and the House majority are possible limits on his testimony, including portions delivered in closed session.

This news should prompt close attention to the role Mueller can most constructively play from this moment on, now that he has concluded his inquiry and written his report. The time may have arrived to phase out the intense focus—the “Mueller-centricity”—that has so long dominated the debate over the Russia-Trump campaign alliance and the president’s acts of obstruction.

What worries Mueller about the requested testimony? Of course, he fears the political circus: a hearing in which the majority and minority clash with Mueller caught in the middle and unable to deliver a clear or coherent narrative. Rather than clarify issues and questions left open in the report, the hearing could compound the confusion and supply ammunition for another round of unedifying political claims and counterclaims. He may also worry that classified information cannot be adequately protected in this setting. He could be asked questions he cannot answer in public, with the result that he may appear evasive or that his refusal to respond will encourage irresponsible interpretations of the reasons for his silence.

The testimony also would not be entirely congruent with the conception of the special counsel’s role as defined by the governing regulations, which anticipate that the special counsel will set forth his conclusions only to the attorney general. Unlike the independent counsel model, Mueller does not have independent obligations to disclose information to Congress or the public, nor does he have the discretion to determine those parts of his work he might provide outside the Department of Justice. Of course, Congress has every right to call for his testimony, and it has done so. But when he does appear, he will be stepping outside the role envisioned for the counsel. This may add to Mueller’s discomfort as a law enforcement professional known to prefer “going by the book.”

For these reasons, when Mueller does testify, he may decline to part significantly from the material presented in his report. He wrote what he wrote. It is worth recalling that when Mueller sent Barr a letter questioning the attorney general’s four-page summary of the report, he stressed the language of the report itself. From his standpoint, what he had already written, in the final report that he submitted to the attorney general, was the best statement of his findings. It would be curious if the scrupulous Mueller would take the occasion of public testimony to riff on his report. It is far more likely that he would stick to the script.

If he largely uses any testimony to rephrase what appears in his report, critics of Trump may become enraged that, one more time, Mueller left them disappointed. Republicans intent on diverting attention from the damaging material in the report will revel in this disappointment.

By contrast, if Mueller decides to elaborate on his conclusions, the outcome may not be any more productive. Democrats may push him to put the finest possible point on those elaborations while Republicans accuse him of going beyond his brief. Then the country will face the inevitable if misleading charge that Mueller has editorialized in the style of James Comey’s press conference comments decrying Hillary Clinton’s “carelessness.” For the first time in his investigation, Mueller will have been made a party to a press event not of his own choosing, and any comments he offers beyond the ground covered in his report will open him up, however unfairly, to the claims that he is a prosecutor “gone rogue.” The outcome of all this could be less, not more, public clarity about Mueller’s conclusions.

This is not to suggest in any way that Mueller should not testify. It is to strike a note of caution about importance to be attached to that testimony. Mueller did his job and laid out at length, in more than 400 pages, his analysis and the conclusions he was prepared to reach. Now Congress has its own responsibilities, which Mueller should not be expected to assume on its behalf. As Walter Dellinger has pointed out, Mueller’s report contains massive amounts of material upon which Congress can make various investigative and oversight judgments.

Those judgments can include the initiation of an impeachment inquiry, or escalation in that direction if Congress cannot overcome, through negotiation and accommodation, the administration’s refusal to cooperate with its investigation. If Congress elects not to pursue impeachment, it still has the option of censure, a response to the Mueller report that has generally underrated potential. A carefully structured censure resolution puts Congress on record on the activities that should not, for want of congressional action, pass as acceptable.

So, yes, Mueller should testify, but expectations should be set realistically, and Congress should not suggest that it is overly dependent on that testimony in its assessment of the import of his findings or the next steps in responding to them.

There is one clear public service that Mueller could render with his testimony and which would present none of the problems that seem to be troubling him as he negotiates his appearance with the House. He could reflect on his experience operating under the current special counsel rules.

Written to provide for an independent law enforcement function in cases like this one without the excesses of the old independent counsel statute, the regulations do not provide for the special counsel to report directly to Congress or the public, or to identify and assess potential grounds for impeachment. They provide some but not extensive guidance on the scope of the attorney general’s supervision.

This is the question Mueller could be asked that he could freely and constructively answer: Given the purposes of the regulations, how would you consider revising them in the light of experience to better achieve those objectives?

Most critically, Mueller could clarify the impact on the special counsel’s work of the Office of Legal Counsel (OLC) opinions that purport to immunize the president from criminal prosecution while in office. When addressing this issue, he will almost certainly seek to avoid being baited into suggesting that, but for the opinions, he would or would not have prosecuted the president on this record. But he can provide useful information on the ways in which the opinions could be clarified or improved, with particular attention to his view that they blocked him from reaching a final conclusion about the obstruction issues. He might be asked, for example, whether he checked with OLC on his reading of the opinions and the limits that, in his view, they imposed.

In this way, Mueller’s testimony could provide an opportunity to look ahead, not only back, and help with the next stage in the difficult task of designing procedures to hold presidents and other senior executive branch officials accountable for compliance with the law. The independent counsel rules did not work for one set of reasons; now, for different reasons, the special counsel rules have also been shown to be flawed. Robert Mueller can help fix them.