The decision was likely made for practical reasons, such as making it easier to call witnesses to testify, and does not necessarily indicate that the former FBI chief is ready to issue indictments, experts say.
“When conducting an investigation, prosecutors commonly work with a grand jury,” said Melinda Haag, former U.S. Attorney in San Francisco. Because of its significant legal power and investigative reach, Haag says, impaneling of a grand journey can happen at almost any point during an investigation—not just near the end.
The use of grand juries, which serve as forums for testimony and evidence gathering before a potential trial, is not uncommon in federal cases. It’s a unique environment with special rules: because there are no defendants, legal counsel is not present, and the prosecutor has significant control over the proceedings. The process can lead to indictments if criminal evidence comes to light.
In part because it echoes the events of Watergate, Mueller’s decision to specially impanel a grand jury has been seen as revealing. That means that Mueller opted not to use a sitting grand jury to handle the case, or continue using the grand jury in Alexandria, Va., that had been used by federal prosecutors to investigate former national security advisor Michael Flynn.
But while the special formation of the jury is a highly visible and certainly important move in the ongoing investigation, it may be less dramatic than it initially appears.
“Given the nature of the things that Mueller is investigating, it would be odd for him not to use a grand jury in the District of Columbia,” said David Sklansky, a co-director at Stanford's Criminal Justice Center, adding that it would be “weird” for Mueller to rely on a standing jury for the investigation.
There are a number of reasons for that. Under law, grand juries are held to a certain term length and sometimes called to multiple cases, so for a complicated and potentially lengthy investigation it makes sense for a prosecutor to convene a new jury that can devote its entire term and attention to a single case.
And a sitting jury would not have been screened for participation in a high-profile and high intensity case like this one. A dedicated grand jury will be an “administrative convenience,” in a case that could involve numerous documents and participants, said Robert Weisberg, a criminal justice expert at Stanford Law School.
At an extreme, the formation of the jury could mean that Mueller believes he has—or could soon have—enough evidence to issue an indictment that could lead to a criminal case, says Hadar Aviram, a law professor at UC Hastings. But it could also simply mean the Mueller is hoping to utilize the powerful evidence-gathering machinery that a grand jury provides.
Aviram calls the grand jury process “a powerful mechanism that has the capability of generating more evidence” through its powers of subpoena, meaning the prosecutor can compel testimony and the handing over of documents. The latter is particularly potent, because, unlike with testimony, it’s nearly impossible for documents to be protected under the Fifth Amendment. And Weisberg points out that because those who testify are under oath and could end up as defendants in a later trial, and prosecutors can grant immunity in exchange for testimony, the grand jury tends to be a productive environment for revealing testimony and naming of further witnesses.
But Haag emphasizes that the impaneling may simply mean that Mueller plans to start subpoenaing documents—and, “even if they are at a stage where they want to take testimony from one or more people, that, too doesn’t mean they’re reaching the end of the investigation.”
Regardless of the strategy behind the formation of the grand jury, many aspects of it will be mysteries for some time. The proceedings could be lengthy and are legally protected under strict rules of secrecy—though witnesses are free to talk about their participation. If witnesses do choose to disclose their involvement, or any details of the subpoenas are leaked, it could provide clues into the shape of the investigation.
But for now, we’re mostly in the dark.
“Everything is just a kind of tea leaf reading at this point,” Wesiberg said—adding that any conclusions should be drawn “with caution.”