In its first Jan. 6 jury trial, the Justice Department prevailed on one of the legal theories best designed to eventually snare defeated former president Donald Trump and his top cronies: obstruction of Congress’s electoral vote tabulation. Meanwhile, the the Justice Department announced a new indictment and arrest relying on that same theory. If Trump is going to be indicted, this charge is one of those most likely to be included.

A unanimous guilty verdict against Guy Reffitt, the first involving a Jan. 6 defendant, should send a stark warning to Trump insurrectionists. Juries are ready to convict those who tried to stop the electoral vote count. In a statement, the FBI’s Washington field office advised that the verdict “should serve as a reminder for others who committed crimes at the Capitol that day that these are serious charges and that the FBI and our law enforcement partners will do what it takes to hold them accountable.”

Reffitt’s trial, as the New York Times reports, “offered an early glimpse of the exhaustive evidence that prosecutors have collected. The week-long proceeding featured testimony from police officers, a Secret Service agent, one of Mr. Reffitt’s compatriots in the Texas Three Percenters militia group and Mr. Reffitt’s teenage son.”

In this case, the evidence served to connect Reffitt to his underlings and fellow rioters. However, the extensive evidence gathered by the Jan. 6 committee most likely includes communications between Reffitt (or other riot leaders) and those up the chain, including any members of Congress and administration officials involved in trying to overturn the election results. The FBI will have ready access to that evidence if Congress makes a criminal referral.

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Ten federal judges have allowed the obstruction charge, including the judge in Reffitt’s trial (who might still choose to throw out the charge). Only one has refused to allow the charge in conjunction with the Jan. 6 insurrection. With success in one trial, the Justice Department will be encouraged to use it in further indictments.

Another development suggests that the Justice Department is expanding its inquiry to those not present at the Capitol. On Tuesday, the Justice Department announced the indictment and arrest of Henry “Enrique” Tarrio, the former national chairman of the Proud Boys. (A superseding indictment was also announced for five other participants already in jail.)

“Tarrio and his co-defendants, all of whom were leaders or members of the Ministry of Self Defense,” a Proud Boys subgroup, “conspired to corruptly obstruct, influence and impede an official proceeding, the certification of the electoral college vote,” the Justice Department statement said. It added, “Although Tarrio is not accused of physically taking part in the breach of the Capitol, the indictment alleges that he led the advance planning and remained in contact with other members of the Proud Boys during their breach of the Capitol.”

Trump should be forewarned: He and his co-conspirators not physically present might find themselves looking at a similar charge.

Unlike Tarrio, Trump was physically present at the Stop the Steal rally ahead of the Capitol breach, and exhorted the crowd to march to the Capitol. Two legal theories — obstruction of an official proceeding and seditious conspiracy (which has been filed against other defendants) — rest on the argument that Trump wrongfully set out to stop the vote tabulation that would confirm President Biden’s election. In the case of seditious conspiracy, prosecutors would need to show that Trump knew his actions would result in the violent insurrection.

Stumbling blocks to prosecuting Trump remain. For an obstruction charge, prosecutors would need to show he intended to corruptly interfere with Congress (e.g., he knew there was no basis for blocking the vote). Evidence that at least 11 officials (including then-Attorney General William P. Barr) told Trump he lost does not rule out the possibility that he simply refused to believe them. (Put differently, he was so loony he couldn’t tell fact from his own fiction.)

For seditious conspiracy, prosecutors would most likely need to show that Trump knew violence would occur — or, when it broke out, that he aided the insurrectionists. Evidence for that might come from communications between Trump associates or from participants in conversations with Trump.

In sum, the Justice Department is establishing the legal theories that could be used to follow the chain up to and including Trump. This is standard practice in mob trials. But it still leaves knotty questions regarding intent.

However, the notion that Attorney General Merrick Garland is slow-walking charges against Trump or has decided not to go after him is inconsistent with the department’s actions to date. Garland might just be warming up to take on the man whose refusal to accept defeat resulted in the most lethal armed insurrection since the Civil War.