But grand juries are shrouded in secrecy — necessarily so, as it turns out. That also means it can be hard to get a handle on how they work and why they are important — even vital — to the investigation into whether the Trump campaign colluded with Russia and/or obstructed justice after the fact.
We attempted to lift the curtain by calling former federal prosecutors, defense attorneys and FBI agents. Here's how grand juries work, for those of us who just pretend to know how they do.
You can't be charged with a federal crime without one: A grand jury must sign off before prosecutors can charge anyone with a federal crime. It's a constitutional right afforded every American, said Asha Rangappa, a senior lecturer at Yale and a former FBI special agent. Some states require a grand jury to approve charges, too.
How it works, in 3 steps:
1. Prosecutors ask a judge to impanel (legalese for “set up”) a grand jury for an investigation.
2. If a judge agrees, prosecutors present their evidence, like documents and witnesses, to jurors.
3. At the end of the process, the jury either hands down an indictment or doesn't.
From there, charges are announced, and the legal process we're more familiar with (a trial, for example), begins.
Grand juries are made up of people like you and me: People can get summoned to grand juries like they can to regular juries. The juries typically consist of 16 to 23 people. You need 12 to vote out an indictment, and the standard is probable cause, said white-collar defense attorney Jeffrey Jacobovitz.
In other words, grand juries are not deciding whether someone is guilty.
The grand jury is not a trial: That comes later. So when witnesses are called before the grand jury (if they have lawyers), their lawyers have to wait outside while prosecutors question them.
Grand juries are designed to be checks on prosecutors: The idea is that the American people must sign off on their government charging someone with a crime. But grand juries are minimal checks. There are no defense attorneys present, and so prosecutors are usually successful in getting a grand jury indictment.
It's supposed to be that way, said Alex Whiting, a former federal prosecutor and current professor at Harvard Law. If you started allowing witnesses to defend themselves in a grand jury, then suddenly you're holding something that more closely resembles a trial.
Plus, Whiting said, the mere existence of grand juries act as a check on prosecutors. When gathering evidence, prosecutors know they're going to have to convince a grand jury there is reason enough to charge someone.
Grand juries are typically secret: When grand juries are impaneled, the judge, prosecutors and the jury are supposed to be the only ones who know about it. (News leaked of the grand jury Mueller impaneled for the Russia investigation in August, when the Wall Street Journal reported it.)
The secrecy is necessary, because a grand jury doesn't mean someone will be charged with a crime. “If a prosecutor does an investigation of somebody and the grand jury decides there's not enough evidence, nobody should ever hear about it,” Whiting said. “It just goes away.”
Grand juries are great for getting witnesses to tell the truth: Because they are so secretive, and because there are no defense lawyers, witnesses usually have no idea what prosecutors know they know.
So, Whiting said, “It's very hard to lie when you don't know anything about what the prosecutor knows or what the charges are.”
Grand juries are excellent investigative tools: If serving as a check on prosecutors is a grand jury's first job, helping prosecutors investigate complex cases is its second job.
Through a grand jury, a prosecutor can subpoena witnesses and documents. Whiting said they're essential to investigating complex crimes “in the face of actors and witnesses who are doing everything they can to hide what they are doing.” Think: organized crime, terrorism, financial fraud, political corruption.
A grand jury was set up to investigate Michael Flynn: This one was impaneled before the Justice Department appointed Mueller to investigate Russia meddling, and it's separate from the grand jury Mueller impaneled to look at Russia.
But a grand jury did not end up indicting Trump's former national security adviser, Jacobovitz pointed out. That's because there was no need for prosecutors to press charges. Flynn pleaded guilty to lying to the FBI as part of a deal to cooperate with investigators and ostensibly avoid those serious charges.
Grand juries are routine: I asked Whiting if the existence of a grand jury in the Russia investigation lets us infer anything about the intensity of the investigation. Whiting said it doesn't.
“It doesn't mean that there's going to be anybody to charge in the Russia investigation or that he'll prove collusion. All it means is he needs a grand jury to gather all the information … to get to the bottom of it. In these sorts of investigations it's very routine,” Whiting said.
So even though we may now understand what role a grand jury plays in the legal process, we will probably never know what goes on behind closed doors in each grand jury.