Attorney General William P. Barr is testifying before Congress on Wednesday for the first time since he released special counsel Robert S. Mueller III’s report last month. And lawmakers have a lot of questions for him.

Barr’s testimony is highly anticipated. Experts say it could help us understand some key decisions made by the Justice Department about the Mueller report. The special counsel’s report on Russian election interference was much more damaging to President Trump than Barr originally let on, raising questions among legal experts and Democrats about where Barr’s loyalties lie. Mueller himself was upset with how Barr characterized the report to the public.

Barr will be speaking Wednesday to a Republican-controlled committee in the Senate. (He is also scheduled to testify Thursday before a Democratic-controlled committee in the House, but he’s arguing over format and threatening not to attend.)

Here are six questions that legal experts say Congress must ask:

1. Why did you originally indicate that Mueller was conflicted on whether Trump obstructed justice?

In a letter summarizing the report weeks before it was released, Barr underscored how Mueller laid out evidence on “both sides” of whether the president was guilty of a crime. This gave the impression that Mueller was conflicted. But that’s not really true, as The Fix’s Aaron Blake notes.

Mueller spent significant time detailing how the president, in his words, tried to “control” the independent investigation. The report outlines 10 instances in which Trump tried to add roadblocks or even end it altogether by firing Mueller. Rather than being conflicted about Trump’s intent to commit a crime, Mueller appeared to be hindered by Justice Department guidelines that you can’t indict a sitting president.

“There is now public confusion about critical aspects of the results of our investigation,” Mueller wrote to Barr after the summary was released.

2. Why did you think it was your responsibility to make the ultimate decision about whether to prosecute the president for obstruction of justice?

As Jessica Levinson, a professor at Loyola Law School, notes, Mueller determined he didn’t have authority to recommend charging Trump with a crime, but that Congress could. In fact, the report strongly suggests Mueller thinks Congress should do something about it.

The conclusion that Congress may apply the obstruction laws to the President’s corrupt exercise of the powers of office accords with our constitutional system of checks and balances and the principle that no person is above the law.
The Mueller report

Instead, Barr publicly said he wouldn’t be charging Trump with obstruction of justice, weeks before he released the report. That left plenty of time for Trump and his allies to form the incorrect narrative that the Mueller report exonerated him.

3. Why did you summarize the report in a news conference after saying you didn’t want to summarize the report?

Barr was widely criticized for releasing four pages summarizing a 400-page report weeks before he released it. He split hairs by telling Congress he wasn’t summarizing the whole report; he just wanted to get the bottom-line conclusions out there because of the great public interest.

Never mind that that’s a distinction without a difference. Barr threw his “no summary” rule out the window the morning he released the report. Hours before, he held a news conference that characterized the report in decidedly pro-Trump language. (He even ripped the term “no collusion” right out of Trump’s Twitter feed, despite the fact that collusion isn’t a legal term. And he spent significant time talking about how the president “was frustrated” by the Mueller investigation.) This question gets to the heart of Democrats’ concerns that Barr has prioritized pleasing Trump over being an impartial attorney general and thus impartial arbiter of what the public can see in the Mueller report. Speaking of …

4. Why can’t Congress see the full, unredacted Mueller report?

Barr has cited a few areas where information can’t be shared — including grand jury testimony and evidence, which is normally kept private, and information that could hinder ongoing investigations. House Democrats set a deadline for Wednesday to see the full report, and they’ve issued a subpoena to force Barr to hand it over. Congress could even take Barr to court over their right to see it. Legal experts say there is a world in which Congress has a right to see the full report, especially if they’re using it for impeachment proceedings. (It’s a much tougher argument to make that the public should be privy to classified and grand jury information.)

5. What was the nature and extent of your contacts with the White House during the period between when you received the Mueller report and when you released the redacted version?

This question comes from Josh Chafetz, a law professor at Cornell University and expert on Congress’s constitutional rights. Barr said that White House lawyers got to see the report — before even Congress. The unanswered question is what role, if any, the White House had in trying to frame this report and its redactions, ostensibly in a positive light for Trump.

6. What are the legal theories upon which you and Mueller disagreed?

When Barr did acknowledge in his news conference the more damaging parts of the report for Trump, he qualified them by saying he and the No. 2 at the Justice Department, Rod J. Rosenstein, disagreed on some of Mueller’s “legal theories.” Levinson wants to know what, exactly, Barr disagreed with Mueller on.