Nope, you guys are in charge. Totally.
You can issue subpoenas, question witnesses, etc.
Now often a Grand Jury is called upon for a single case, and the jurors, with their measly $15 a day pay will seek to get it over as fast as possible. But that is by no means required.
The “Joke” about the ham sandwich is exactly that- a joke. It does not reflect reality.
At least at the federal level, witnesses are not under any obligation of secrecy. They’re free to go on the evening news that day and tell everyone what they were asked.
I suspect how in charge the jurors are and whether they know they are in charge and what they are going to do depends very much on exactly what sort of grand jury they are on. I’ve been on grand jury duty at least 3 time - and two of the times , they were seeking jurors who could sit on a grand jury that was going to look at a group of related crimes. That grand jury was expected to meet once or twice a week for approximately six months - and they may have called witnesses, asked questions and issued subpoenas.
The three grand juries, I sat on however, were very different. Our term ended up being 10 days total of jury duty, and each day multiple cases were presented to us. Getting it over quickly wasn’t a factor - our term was our term and there were always cases to be presented. Very occasionally a defendant testified , but there isn’t going to be any investigation by the grand jury in most cases- the purpose of the grand jury is to determine if there is enough evidence to go to trial , not to hold the trial. The defendant was only present if he/she testified, the defense lawyer wasn’t in the room at at all , the prosecutor determined who the witnesses were and what questions they are asked - which has an effect on what the grand jury can do. After all, if you never hear the defendant provided an alibi, you can’t subpoena the person who might establish that alibi.
So the “joke” often isn’t really a joke - it’s accurate.
I was on a special grand jury that meet every Wednesday afternoon for several months. I read the paperwork. And yes, legally, we had the power to direct the investigation ourselves. In practice, we did not. We weren’t lawyers. We didn’t have any of the background. We didn’t have a leader with any interest in leading. In practice, we rubber stamped what the da asked us to rubber stamp, after seeing evidence that he gathered and talking to people he brought to us.
I was one of the few jurors who ever voted against the da’s recommendations, some of which were very weak, imo. The only time the jury, as a group, didn’t follow the lead of the da was the second time he asked us to extend our term, when we voted “no”.
It’s not a joke. There is a real limit on what charges a da can being because he does need to get that rubber stamp, and if he’d just asked for random political hit jobs (for instance) instead of overblown charges related to evidence of actual bad actions, we might have had the spine to say, “no”. But i don’t think a da needs a lot of evidence to get an indictment. And the odds of an indictment the da doesn’t request are close to nil.
So the prosecutor generally does, say, 80% of the evidence-finding, while the grand jury’s job is to analyze and assess the info brought by the prosecutor, while also digging for the remaining 20% of facts of the case by themselves?
In our case, it was more like 95% 5%, if we even did that much. The only thing we did on our own was pick the questions we asked of the witnesses the da brought to us. And once or twice we asked to see a transcript of a prior session.
I think that in the significant majority of criminal cases, the prosecutor (or really case agent) does close to 100% of the evidence-gathering and then presents (some subset) of that evidence to the grand jury. You’re not going to use a grand jury subpoena for an unlawful reentry case, or a felon-in-possession case, or something similarly common and mundane (yet still felonious and federal).
I don’t know if there are statistics, but I’d be surprised if a significant overall percentage of evidence in federal criminal cases is obtained by grand jury subpoena. I’ve mostly seen them used for long-term, large-scale (generally white collar and/or corporate) investigations, but that’s purely anecdotal.
Michael Cohen, for example says that he pled guilty because the DA threatened to indict and convict his wife on similar charges, because her name was also on the home equity loan account he used (behind her back) to get the money to pay off Stormy, so he would ahve bankrupted them trying to defend her from bogus charges. The fact that the DA could even threaten such charges, must mean he thought Cohen and wife were ham sandwiches, despite her being kosher. (DA’s do have this sort of vicious overreach, see Aaron Schwarz case).
But I digress. We’re still not answering the OP’s question. I can see with campaign finance, or SEC embezzlement cases, etc - that a grand jury session precedes an indictment, then they arrest. When someone is caught doing some horrible, unspeakable crime (hijack? planting a terrorist bomb? Trying to light their shoe-bomb or underwear bomb?) how does the requirement to arraign within 48 hours (give or take) or else release, align with the grand jury requirement? Do they have a GJ on standby around the clock? Don’t they need charges to hold them?
Arraignment is not the same as indictment. According to this in a Federal case, a person must be indicted within 30 days of arrest. The initial arraignment (also called a detention hearing ) must take place within 48 hours, and there’s a second arraignment hearing that takes place after the indictment
On the contrary, I think the OP’s question has been long-since answered.
You go before a judge and argue why the public needs for this guy to be held in jail pending charges. It’s not a mystery.