(CNN) The Justice Department's response to the January 6 US Capitol assault meets one of its biggest tests yet with prosecutors presenting their case for why the alleged plotting of several far-right militia members ahead of the attack amounted to a seditious conspiracy.
The charge has rarely been brought in the century and a half that the statute and its forerunners have been on the books. By using it against members of the Oath Keepers the Justice Department is expressing that it sees the breach of the Capitol as a grave threat to the operation of the US government.
"They concocted a plan for armed rebellion to shatter a bedrock of American democracy," prosecutor Jeffrey Nestler told jurors Monday morning as the trial began.
"To charge someone with seditious conspiracy is to send a signal that not only have they done a bunch of bad stuff," said Alan Rozenshtein, a former official in the Justice Department's National Security Division, "but that they've done bad stuff that rises to the level where we as the government want to express that this is an attack on the basic functioning of a democratic system and is even more dangerous for that reason."
Attorney General Merrick Garland balked at initial efforts to add the charge to Oath Keepers case, CNN previously reported, but as the case developed, investigators were able to build out the evidence with cooperators and internal communications. The charge was added in a superseding indictment unveiled in January.
That symbolic significance will be lingering over the trial happening in the DC federal courthouse -- beginning with opening statements Monday -- in the coming weeks. There, five alleged members of the Oath Keepers, including leader Stewart Rhodes, will face a jury considering whether to convict them of the charge and of other alleged crimes.
They're accused of planning to use force to stop the lawful transfer of presidential power, with the grand jury indictment alleging that they "coordinated travel across the country to enter Washington, DC, equipped themselves with a variety of weapons, donned combat and tactical gear, and were prepared to answer Rhodes's call to take up arms at Rhodes's direction." The defendants have pleaded not guilty.
Before the Justice Department unveiled the seditious conspiracy count against Rhodes and several other far-right activists, there had been significant handwringing among the legal observers about the absence of the charge that, by its name alone, carries palpable political weight.
"I don't believe that it was done without a lot of thought put into it. It has a shock value," said Jeffrey Ian Ross, a criminologist at the University of Baltimore.
The bread and butter of the Capitol mob prosecutions so far has been an obstruction statute, commonly used for witness tampering, that has been used to accuse the rioters of interfering with an official proceeding. Misdemeanors for unlawfully parading in the Capitol and disorderly conduct have also been used as low-hanging fruit against January 6 defendants, and those who acted violently during the breach have faced assault charges and the like as well.
Securing a jury conviction of the seditious conspiracy charge could help justify how the Justice Department has conducted its January 6 investigation and rebut claims that the riot was merely a protest that got out of hand.
"It does have this term 'seditious conspiracy,' and so that sort of brings to mind this broader issue of sedition: that you have somehow sort of betrayed the government in in some way," said Carlton Larson, a law professor at the University of California at Davis and an expert in treason law.
Three Oath Keeper defendants have already pleaded guilty to the charge. It carries a maximum punishment of 20 years in prison.
The history of the seditious conspiracy statute dates back to the start of the Civil War, when Congress made it a crime to conspire to overthrow the US government or to conspire to use force to "prevent, hinder, or delay the execution of any law of the United States."
In the infrequent cases that prosecutors have brought the charge, they have not always been successful securing a conviction.
The last time it was charged -- against a Michigan militia accused of plotting an attack on law enforcement -- the count was dismissed by a judge in 2012 who said the Justice Department failed to show that there was a "concrete agreement to forcibly oppose the United States government."
The way allegations of seditious conspiracy may run into constitutionally protected free speech can pose a problem for prosecutors, according to Mark Satawa, one of the defense attorneys who represented the Michigan militia members.
"The act of speaking, the act of talking about something -- and that something may be the overthrow the United States government -- but it's still talking," he told CNN. "And so the act itself runs afoul of these very deeply held beliefs that we have as a people, this idea that we should be able to bitch about our government."
In the January 6 case, prosecutors are pointing to alleged statements from Rhodes calling for a "civil war" to stop the certification of President Joe Biden's win, as well as concrete steps the Oath Keepers are accused of taking to plan for a violent encounter.
Much of the legal debate over the charge centers on what exactly the Oath Keepers were plotting to do, as the statute addresses conspiracies aimed at impeding the government's ability to do its business. Because the charge is so rarely brought, there is little case law fleshing out the parameters of the crime.
The defense attorneys argued in pretrial proceedings that Congress' Electoral College certification ceremony did not meet the statute's standard for an execution of a law -- an argument Judge Amit Mehta rejected in declining to dismiss the count.
Outside experts see the legal case for this particular seditious conspiracy charge as especially on point, in part because of the nature of the government operation the defendants were allegedly seeking to disrupt.
The alleged conduct, Rozenshtein said, was not aimed at personally enriching the defendants.
"It was more an ideological objection to the government doing not just any law, but one of the most foundational laws in American democracy, which is the peaceful transition of power."
The Oath Keepers' attorneys have signaled a defense that will argue that that the activists, in their preparations for January 6, were not intending to disrupt government operations, but were readying themselves to respond to any invocation by then-President Donald Trump of the Insurrection Act.
Mehta is allowing that defense to a limited extent, but ruled the Oath Keepers could not discuss the legality of or what's required to invoke the law, which authorizes a president to deploy state militias to suppress rebellions against the government.
Even if the Justice Department's theory of the case meets the legal definitions of seditious conspiracy, getting a conviction also requires convincing the jury that there is evidence to back up the allegations.
Because of the reservations jurors may have about criminalizing political speech, prosecutors will need to go above and beyond with the evidence they present, according to Satawa.
"I think they're looking for pretty persuasive, maybe even overwhelming proof that this person truly intended to incite a rebellion or overthrow the government before they're going to convict them of talking, and particularly convicted of committing a crime of an agreement to talk," Satawa said.
There have been indications that the defense will argue that the Oath Keepers entered the Capitol not to disrupt the certification proceeding, but to aid law enforcement battling the mob.
Prosecutors, meanwhile, have previewed the use of communications between some of the defendants during the breach that the government says shows that the aim of their actions in the Capitol was to target lawmakers. They've signaled intentions to play for the jury video from the attack as well.
The indictment indicates investigators also obtained pre-January 6 encrypted text messages showing the alleged planning for the attack, as well as evidence around militia training sessions and the purchase of firearms and tactical gear ahead of January 6. Prosecutors are additionally expected to put on the witness stand Oath Keepers who pleaded guilty and are cooperating in the case.
Rozenshtein argued that the evidence the jury will be considering is straightforward and what makes the case feel novel is how rarely there is a circumstance that warrants bringing the charge.
"It's not that it's hard to prove seditious conspiracy. It's just a criminal charge, like anything else. If you have the facts, you can prove it," he said. "It's just that generally, we haven't seen a lot of ... forced ideological attempts to keep the government from doing its business, in a way that rises to the level of seriousness that DOJ thinks that it's appropriate to bring."