Special counsel Robert S. Mueller III’s report on his Russia investigation is expected soon, and it’s also expected that we won’t see it — at least not right away. Attorney General William P. Barr said at his confirmation hearing that, under Justice Department rules, the report should be treated as confidential and that he is constrained in summarizing its contents to Congress and the public. In sum, it means we might not learn a whole lot about President Trump.

But there will be a fight over this, and now Democrats say that fight will include Mueller testifying to Congress.

House Intelligence Committee Chairman Adam B. Schiff (D-Calif.) said Sunday that, in addition to subpoenaing the Mueller report, “We will bring Bob Mueller in to testify before Congress. We will take it to court, if necessary.” House Judiciary Committee Chairman Jerrold Nadler (D-N.Y.) also signaled last month that Mueller could be called to testify.

But what might this mean, practically speaking? To the untrained eye, this would seem a clever workaround. If Mueller’s report can’t be released, Congress can just force him to testify all about it, right?

As with all things in the Mueller probe, though, it’s not the simple. There are plenty of reasons to believe Mueller would be similarly constrained — and restrained — in his testimony.

Some of the reasons are the same as with his report. The special counsel statute he’s working under — which is different than the one independent counsel Kenneth Starr operated under in the 1990s — says decisions about disclosure are left to the attorney general (Barr) and not Mueller. This was in part because Starr’s public comments about his investigation were seen as overzealous.

Also, Rule 6(E) of the Federal Rules of Criminal Procedure say information obtained via grand jury can’t be disclosed except via court order or to prosecute someone. And given Justice Department rules say a sitting president can’t be indicted, any crimes Trump might have committed won’t be prosecuted.

So what about non-grand jury materials, like voluntary testimony? Justice Department policy also prohibits disclosure of information that does not lead to a prosecution. And what’s more, it cautions its personnel against taking actions that could influence an election — which could apply with the 2020 campaign getting off the ground.

These were policies that then-FBI Director James B. Comey flouted when he disclosed information about the Hillary Clinton email investigation on the eve of the 2016 election. But that’s also the point: He was stepping outside the usual guidelines. Mueller, on the other hand, is known to be a very by-the-book type of prosecutor, and he will be working with an attorney general who, while saying he wants to release as much as he can, has made clear he thinks there are real and significant constraints.

It’s theoretically possible Barr could authorize Mueller to say more, but why would he hold back on detailing the Mueller report but then let Mueller the witness have free rein? Congress could also seek a court order to get around disclosure rules, but that’s probably unlikely too, according to former federal prosecutor Patrick J. Cotter.

“While I personally think it would be a very good thing for the country to have our elected officials learn what Mueller has found,” Cotter said, “the truth is that the statute under which he is operating and related law and policy do not support Congress being able to force such disclosure by Mueller.”

Another key question is whether Barr and the Justice Department can simply prevent Mueller from testifying. If he is still considered a Justice Department employee, they could do this while they fight the subpoena in court. If he’s not considered an employee, they can still make requests that he not testify or avoid certain disclosures.

“Mueller is very much an institutionalist, and I think it would be a mistake to expect him to come testify to things where DOJ is asserting a privilege and that assertion is being played out in a court fight,” said former Obama Justice Department official Matthew Miller. “Of course, if he feels that DOJ is doing something inappropriate, maybe that changes things.”

In the end, it’s probably best to view this as a tactic in the context of the burgeoning legal fight. Democrats want Barr to voluntarily release as much as possible and possibly even the full Mueller report. They could also seek a confidential so-called “road map” like the one Congress got with Richard Nixon, which essentially pointed them in the direction of what Nixon had done wrong.

It’s working the refs. They’re essentially signaling that it would just be best to get the information out now, or they’ll use their subpoena powers to try to force the issue — and cause Barr and the Justice Department real headaches. But the idea that Mueller will show up and spill key information is probably fanciful.