On Thursday, Attorney General William Barr is expected to send a redacted copy of special counsel Robert Mueller’s report to Congress. While Barr’s letter said that Mueller’s team had found no chargeable evidence that the campaign conspired with the Russian government in 2016, Trump’s inner circle are reportedly worried that new details about his attempts to obstruct justice would emerge.

During his confirmation hearing last year, Barr had vowed to be as transparent as he possibly could within the bounds of the law. He hasn’t kept his word. Last week, he locked horns with Democrats on the House Judiciary Committee, who have insisted that he hand over the entire report and all of the materials on which it was based. When testifying, he offered a number of legal justifications for why he couldn’t release the full report. A number of outside legal experts, though, say his claims were false.

Last month, Barr released a four-page summary of Mueller’s findings, which Trump then touted it as “total exoneration.” In response, some members of Mueller’s team leaked, through associates, that they were unhappy with Barr’s handling of their report, including his refusal to release multiple summaries that they had written for public consumption. Since then, Barr has claimed broad authority to withhold virtually any damning information about Trump and his associates, at least in theory. Barr said that he had no choice but to redact information that falls into any of these four buckets: information from ongoing investigations; intelligence findings that could reveal “sources or methods”; any information that would “infringe on the privacy and reputational interests of peripheral third parties” who had not been charged with a crime; and grand-jury testimony.

It’s no surprise that the Department of Justice would seek to protect ongoing investigations, but, as House Democrats pointed out, when Republicans held the committee gavels during the previous Congress, the DOJ gave them “thousands of pages of highly sensitive law enforcement and classified investigatory and deliberative records,” many of which “were related to this very same investigation—which of course was open and ongoing at the time [emphasis theirs].”

While the public should never expect to see any classified information that may be contained in Mueller’s report, the House and Senate Intelligence Committees have secure facilities to review classified information, and they do so on a regular basis. What’s more, Vicki Divoll, former general counsel of the Senate Intelligence Committee, wrote in The New York Times that under the provisions of the Patriot Act and the National Security Act, “federal law requires that the attorney general provide to the director of national intelligence any foreign intelligence information collected during a criminal investigation. Then the director must by law provide it to the intelligence committees of Congress.” So not only can Barr release that information to Congress, he must produce it via the office of Director of National Security Dan Coats.

Withholding information that would “infringe on the privacy and reputational interests of peripheral third parties” is the most arbitrary, and potentially the most expansive, of Barr’s criteria. The Justice Department operates under a legal guidance that a sitting president cannot be indicted while in office, so at least in theory Barr could decide that since Donald Trump wasn’t charged with a crime, his “reputational interests” must be protected.

Last week, Barr told members of the Judiciary Committee that he had no choice in the matter because the law requires that a special counsel follow all Justice Department guidelines in the course of an investigation, and they include such a provision. But Columbia University legal scholar Jeffrey Fagan said, in an e-mail exchange, that the guideline is “very elastic.” (Barr cited the furor over James Comey breaching those protocols to reveal such details about the FBI’s investigation into Hillary Clinton’s e-mail server to bolster his argument.) And while Mueller’s team had to abide by that part of the special-counsel statute, the attorney general does not—he has the power to determine that the public’s interest in knowing what happened in 2016 outweighs any individual’s “reputational interests.”

Barr also claimed that a recent court ruling precluded him from releasing grand-jury material. According to the decision handed down two weeks ago, judges don’t have inherent authority to release grand-jury testimony, meaning they can’t order their release for reasons other than those spelled out in the law. But Fagan says that Barr could ask a judge to do so under the existing statute. “All he has to do is be somewhat creative and cautious at the same time, reassuring the court that this is not new law or precedent,” he said, adding: “If he wanted to. Which it seems he doesn’t. Which is not a surprise to anyone. It’s obvious that he’s playing both sides of that divide in this case, employing a strategy tailored to suit his patron at the White House.”

The House Judiciary Committee has authorized a subpoena for the entire Mueller report, and Chairman Jerry Nadler (D-NY) told Politico that they would wait to see Barr’s redacted version before serving it. Barr has taken a good deal of fire from the legal community for his dissembling, and may yet relent. If he doesn’t, we’re heading for a court fight.

And that’s where things may get interesting. One of the exceptions to the law barring release of grand-jury testimony allows a judge to order it unsealed “preliminary to or in connection with a judicial proceeding.” Most legal experts think an investigation by the Judiciary Committee would qualify as a judicial proceeding and that the exception should apply in this case. But if the Department of Justice found the right judge, he or she could see it differently.

If that were to pass, House Democrats would have one trump card in their pocket: impeachment. An impeachment hearing, after all, is unquestionably a judicial proceeding. That was established when a court ordered material from the grand jury investigating Watergate to be handed over to House investigators who were at that point considering impeaching Richard Nixon. In 1974, Federal Judge John Sirica wrote that “it seems incredible that grand jury matters should lawfully be available to disbarment committees and police disciplinary investigations and yet be unavailable to the House of Representatives in a proceeding of so great import as an impeachment investigation.”

Washington is reportedly “bracing” for “Mueller week.” The Wall Street Journal reported that congressional offices “have stockpiled whiskey and drafted pizza orders in anticipation” of speed-reading the 400-page report.

Meanwhile, the White House is preparing a counter-report, and according to The New York Times, “Trump’s plan of attack, aides said, is to act as if the report itself is extraneous to Mr. Barr’s brief letter.” That’s unlikely to fly with Jerry Nadler’s committee, and it looks increasingly likely that the next stage of this two-year saga will culminate in a “judicial process” of one sort or another.