We await news of when Members of Congress will pry sparing and scrupulously parsed testimony from the taciturn Special Counsel Robert Mueller III, and whether it will take a court order — or the House Sergeant at Arms — to get former White House Counsel Donald McGahn before the House Judiciary Committee. But a more likely, and potentially more revealing, witness waits in the wings. As the Washington Post proclaimed earlier this month: “Watergate had the Nixon tapes. Mueller had Annie Donaldson’s notes.”

As McGahn’s chief of staff, Donaldson not only managed an office of dozens of lawyers, but she had a front-row seat as the President raged about Mueller’s investigation. She also witnessed, first-hand, as McGahn (at least by his own and Donaldson’s account) sought to curtail the very worst of the President’s abuses of power. If I were a congressional investigator (and I once was), Donaldson would be high on my witness list.

Donaldson knows as much about Trump’s campaign against the Special Counsel as anyone, and in some ways, she is more poised than either Mueller or McGahn to shed new light on the President’s misconduct. The Office of the Special Counsel cited her notes and testimony nearly 70 times in its report, despite her removed role in the key events the Special Counsel examined. Donaldson’s appearance in the report shows how critical her testimony may be to a determination of whether the President abused his powers. Mueller can tell Congress what others told him, and what documents, like Donaldson’s notes, suggest about the President’s conduct; Donaldson can tell us what she saw with her own eyes. The Special Counsel’s report also suggests that Donaldson may not have her own actions to answer for, at least not to the same degree as other current and former Administration witnesses. In other words, she has less personal incentive to keep quiet.

In fact, Donaldson may have incentives to cooperate. While quite successful, she is not even a decade out of law school and has a long career ahead of her. Reading the Special Counsel’s report, one gets the sense that Donaldson is a smart and careful lawyer — one who can read relevant case law, such as Committee on the Judiciary v. Miers, and recognize that she has no valid claim for resisting a subpoena to testify before Congress. A good lawyer at this stage in her career might reasonably decide that illegitimate defiance of Congress’s constitutional authority is not the way to preserve her career.

The House Judiciary Committee has already authorized a subpoena for Donaldson’s testimony (along with four other Trump-land figures who have long been household names: Steve Bannon, Hope Hicks, Reince Priebus, and McGahn). Despite her attractiveness as a witness, however, and the reasons she may wish to comply, there is a lot of haggling, and likely some litigating, to be done before we hear what Donaldson has to tell about the President’s obstruction of the Mueller investigation.

The President, for his part, says he plans to fight “all the subpoenas.” That includes subpoenas to third-parties who, like Donaldson, have a clear obligation to obey duly issued congressional commands. Trump is already in federal district court in the District of Columbia fighting subpoenas for documents from his accounting firm. While the judge hearing that case has pledged to move quickly, even if he rules against the President, the President will no doubt appeal. While taking a neutral stance in the litigation for the moment, the accounting firm could get cold feet about crossing a President who has repeatedly used the powers of his office to threaten private entities that upset him, and who have paid a financial price for those threats. If the accountants succumb, the House would then have to bring its own litigation to compel production. Cue another round of appeals, and you see where this is going.

And Trump directed McGahn not to testify, even if subpoenaed by House Judiciary Chairman Jerry Nadler. McGahn seems all too eager to accede to his former boss’s wishes, even though he is now a private citizen who can’t be disciplined or fired for insubordination. His law firm, Jones Day, has already lost the Trump Campaign’s business over McGahn’s cooperation — about which the President often boasted — with the Special Counsel. McGahn may view being held in contempt of Congress for failure to testify and litigating against the House over his testimony as less painful than a reputational and financial battle with the man in the world’s largest bully pulpit.

Trump knows all of this, which is why he can so confidently demand illegal defiance of Congress by his former aide. No doubt, Trump will try the same with Donaldson. And the law that applies and the drawn-out legal process it entails are the same for her as for her former boss. What’s different will be the vantage point from which Donaldson will weigh the potential consequences.

Unlike McGahn, her career will not be inextricably linked to her service of the President through to its very end. She can still plot a separate course. And her livelihood, as the partner at a law firm in Montgomery, Alabama, is not dependent on the favor of the mercurial and vindictive Trump and his political allies. Ultimately, she may view the threat of contempt — of either Congress or a court, which when pressed would certainly order her to testify — and the professional and financial consequences associated with it as more weighty than the risk of insults hurled by tweet from a man whose command of the world’s attention will soon enough wane. Aside from those more hard-nosed calculations, Donaldson also could be a lawyer with integrity and weigh nothing but her obligations as a citizen and officer of the court and show up to tell her story to Congress and the American people.

Let’s say she testifies. What will she be able to tell us? That is far less clear than her obligation to go before Congress and take questions.

There is no doubt that at least some of what Donaldson knows about the inner workings of the Trump White House are subject to the presidential communications privilege or the deliberative process privilege. Congress and the Executive have long sparred about the scope of those privileges, but a smattering of judicial opinions since Watergate have sketched their rough edges. And most importantly for our purposes, all of the courts to reach the question have agreed that these privileges cannot be asserted categorically and they are not absolute. (They are, however, still relevant, despite Donaldson’s status as a former White House official. While Judge John D. Bates rejected a claim of absolute immunity from testimony by a former White House Counsel in Miers, he did so by finding no blanket immunity for presidential advisers without any discussion of her status as a former official.)

In other words, the President, who is the only person able to assert the privilege, must do so question-by-question — he can’t use it to bar all testimony from a particular witness or on a particular topic. And any invocation of privilege must be balanced against the constitutionally-based interests of Congress in obtaining the testimony.

That balancing in Donaldson’s case tilts heavily in Congress’s favor. The President’s interest in confidentiality is at its peak when the communications or deliberations he seeks to keep secret pertain to foreign affairs or national security, see United States v. Nixon. Trump’s abuse of his power over the Justice Department pertains to neither.

He still has a legitimate interest in frank advice about the business of the presidency. Without a sufficient showing from Congress, he might be able to maintain confidentiality over much of Donaldson’s potential testimony. But Congress’s interest here is exceedingly strong. The President stands accused of abusing his power to obstruct an investigation into a foreign adversary’s assault on our elections — an assault that is ongoing and that Congress must act to curtail. He did so by meddling in the operations of the Justice Department, which courts have cited expressly as a legitimate target for the House Judiciary Committee’s oversight. See Miers (“given its unique ability to address improper partisan influence in the prosecutorial process . . . no other institution will fill the vacuum if Congress is unable to investigate and respond to this evil”) (internal quotations omitted).

And courts have “routinely denied” claims of executive privilege where the information sought “may shed light on government misconduct” because permitting secrecy under such circumstances “does not serve the public’s interest in honest, effective government.” In re Sealed Case (Espy) (internal quotations omitted). In short, Congress has very good arguments that there’s little the President can keep Donaldson from sharing if and when she appears.

And there’s another issue to consider: the President’s loss of interest in confidentiality through publicity — a relative of waiver that made an appearance in recent litigation on executive privilege vis-a-vis Congress. In rejecting President Obama’s assertion of executive privilege over documents related to a botched operation at the Bureau of Alcohol, Tobacco, and Firearms (dubbed “Fast and Furious”), Judge Amy Berman Jackson of the federal district court in D.C. pointed to a comprehensive report published by the Department of Justice’s Office of the Inspector General. That report detailed not just operation Fast and Furious, but also Department of Justice communications about responses to Congress and the press regarding the operation, and included excerpts from notes and emails sought by the House Committee on Oversight and Government Reform. Publicity of the report, Judge Jackson held, rendered the executive’s interest in confidentiality over related information severely diminished. See Committee on Oversight and Government Reform v. Lynch. Furthermore, the executive branch had cited that report repeatedly in touting its own forthcomingness; it should not then be able to claim that the whole subject matter was off limits to Congress and the public, the court opined. While subject matter waiver doesn’t apply to executive privilege, Judge Jackson seemed to be saying that confidentiality interests in a particular subject matter may still be diminished where sufficient information regarding that subject matter is in the public sphere.

Carry Judge Jackson’s analysis over to a dispute over testimony from Donaldson about Trump’s response to the Mueller investigation, and you can see why the ruling may concern those arguing for secrecy. Mueller has now published a 448-page report, an entire volume of which is dedicated to the President’s abuse of power to interfere with the investigation. That report cites Donaldson’s notes and interviews with the Special Counsel dozens of times. What is more, Trump himself has spoken — and, of course, tweeted — constantly about the investigation, and even about Donaldson’s notes, insisting he didn’t interfere. There is certainly logic to Judge Jackson’s determination that a President who tells his side of the story on a regular basis, and declares a comprehensive report from the Special Counsel to be a “total exoneration,” cannot circumscribe Congress’s assessment of the veracity of his version of those events. Cf. In re Sealed Case (investigation into the veracity of an official’s statements justifies production of records regarding those statements).

For now, of course, the scope of executive privilege applicable to Donaldson’s testimony is purely speculative. We don’t know that Congress will subpoena her testimony, what Members will ask if she appears, nor what she will decline to say. What is not speculative, however, is her value as a witness. And that value will be wasted if she is brought before the House Judiciary Committee simply to decline to answer question after question, and then we all await resolution by the courts of what she can and cannot say.

Donaldson and House Judiciary Committee staff can get in a room together this week. The staff can outline the topics on which they’ll seek her testimony. Where she and her counsel believe there to be potential legitimate claims to executive privilege, they can bring those to the White House for the President’s consideration. If he invokes the privilege, Donaldson and her counsel can weigh that invocation against the case law pointing strongly in the direction of candor before Congress and the public and decide whether the risk of being held in contempt of Congress is one she’s willing to take.

Like many who chose to enter the Trump Administration, Annie Donaldson’s choices ever since have been fraught. Whether to testify before Congress about her time in the White House — and what to say while she is under oath — may be particularly harrowing. Those who have navigated these waters before — John Dean comes to mind — would advise her to steer her own boat to safety rather than taking on water for the President. This President seems perfectly content to watch those who stood by him sink.

IMAGE: Chairman Jerry Nadler (C) speaks as US Attorney General Bill Barr fails to attend a hearing before the House Judiciary Committee on Capitol Hill in Washington, DC, on May 2, 2019. (Photo by Jim WATSON / AFP / Getty Images)