Trump is not going to cooperate with Robert Mueller’s investigation. It’s past time to get over any thought that he will. Once again, Trump and his legal team are tantalizing the public with promises that Trump will answer questions posed by Special Counsel Robert Mueller. The public should expect to be disappointed. The public should also be concerned that acting Attorney General Matthew Whitaker now has authority to block Mueller’s investigative steps, including issuance of a subpoena for Trump’s testimony, and he has no obligation to report his actions to Congress until the conclusion of Mueller’s investigation.

For months, Trump’s team played the press and public with tales of their negotiations with Mueller over the terms for Trump to sit with Mueller for a voluntary interview. Trump consistently fibbed about his eagerness to talk. As I wrote last February, that interview was never going to happen. No minimally competent defense attorney would allow Donald Trump to answer questions in a live setting. Indeed, most would not allow any client who was a subject of an investigation to do so, but Trump poses more than the usual danger as a witness. His inability to stay on topic or control his persistent lying would almost certainly create additional articles of impeachment or form the basis for prosecution once he left office.

His team knows that, yet it has seen value in convincing credulous journalists that it was engaged in good faith negotiations with Mueller over the terms of an interview. Their “negotiations” bought time, during which they could pursue their baseless campaign to delegitimize Mueller’s investigation. While Trump simultaneously expressed his willingness to answer questions and tweeted falsehoods about the “witch hunt,” his team could report that they were continuing negotiations. Finally, Trump stated last week that he was not likely to submit to an interview. This should not have been news.

Meanwhile, his legal team revealed Trump’s willingness to answer limited questions in writing. Written answers, of course, are no substitute for live testimony in which prosecutors can ask follow up questions that dig below the surface of prepared responses. The Trump team purports to be ready to produce Trump’s answers to a narrow set of questions that do not address obstruction of justice. We can expect Trump to reject questions as irrelevant and provide unrevealing answers to the rest.

Why would Mueller accept limited written responses? He may have calculated that they are better than the alternatives.

Mueller’s most obvious alternative is to subpoena Trump to appear before the grand jury. A subpoena, however, is unlikely to produce helpful testimony. By now, Mueller knows far more about Trump’s dealings than Trump does. Even if Trump testified, he would change the subject and forget. He would also lie because he appears unable to help himself. His lies would not advance the investigation, but could provide further fodder for impeachment. That alone, however, is not a good reason to put him before the grand jury.

More fundamental is the fact that Trump likely would not answer questions in the grand jury. Like any witness, he can refuse to answer questions on the ground that he might incriminate himself. That is generally wise strategy for a target of an investigation. Indeed, the Justice Department (DOJ) disfavors subpoenas for targets in the expectation that they will assert their Fifth Amendment right not to incriminate themselves. Negative political consequences would deter a normal president from taking the Fifth, but Trump may calculate that his base will be unaffected by his refusal to participate in this “hoax,” and that he has weakened public support for Mueller’s investigation sufficiently that he can withstand broader political repercussions.

Trump’s team’s delaying tactics also dragged out negotiations until Trump could remove Jeff Sessions as attorney general and install a loyalist who would replace Deputy Attorney General Rod Rosenstein as direct supervisor of Mueller’s investigation. Acting Attorney General Matthew Whitaker now has authority to block Mueller’s investigative and prosecutorial steps if he concludes that they are inappropriate or unwarranted pursuant to DOJ practices. That includes the power to block the issuance of a subpoena for Trump’s testimony.

I have argued that Trump’s appointment of Whitaker backfired because Whitaker’s bias and unfitness for office make suspect the slightest move to limit the investigation. That argument, however, depends on Congress and the public learning about Whitaker’s actions. The special counsel regulations contain a loophole that could allow Whitaker to block a subpoena without revealing his action until Mueller has completed his investigation. Under the regulations, Whitaker must report his refusal to authorize an investigative step to leaders of the House and Senate Judiciary Committees in accordance with 28 C.F.R. 600.9 (a)(3). That subsection imposes a duty to report only at “the conclusion of the special counsel’s investigation.” Whitaker, therefore, already could have blocked a subpoena or taken other steps. His obligation to report does not kick in until Mueller calls it quits. Barring a leak, Congress and the public would be left in the dark.

With Rosenstein as his supervisor, Mueller could assume the ability to seek a subpoena, while anticipating Trump would engage in a protracted court battle to block it. Even that was not an appealing prospect. Whitaker’s appointment creates the real possibility that he would not be allowed by the attorney general even to request a subpoena, particularly since Whitaker can keep his action secret until the investigation’s completion. Without the threat of a subpoena, Mueller would lose any bargaining power he had to obtain voluntary cooperation, as well as the ability to compel testimony. Written answers may be the best he can get. The stonewall, which looks a lot like obstruction, rolls on.

Bill Yeomans is the Senior Justice Fellow for Justice at Alliance for Justice. He previously taught constitutional law, civil rights, and legislation at American University Washington College of Law. He also served for 26 years in the Department of Justice, where he litigated cases involving voting rights and discrimination in employment, housing, and education, and prosecuted police officers and racially motivated violent offenders before assuming a series of management positions, including acting Assistant Attorney General. For three years, Bill served as Sen. Edward M. Kennedy’s chief counsel on the Senate Judiciary Committee, and has also held positions at AFJ and the American Constitution Society.