A second federal judge in Washington questioned whether the lead felony charge leveled by the government against Capitol riot defendants is unconstitutionally vague, as 18 Oath Keepers accused in a conspiracy case urged the court on Wednesday to toss out a count carrying one of the heaviest penalties against them.

U.S. District Judge Amit P. Mehta asked how federal prosecutors distinguish felony conduct qualifying as “obstructing an official proceeding” of Congress — punishable by up to 20 years in prison — from misdemeanor offenses the government has charged others with, such as shouting to interrupt a congressional hearing.

“Essentially, what you said is, ‘Trust us,’ ” Mehta said. “. . . And that is a real problem when it comes to criminal statutes, to suggest, ‘We know it when we see it, and we’ll pick and choose when it is an appropriate exercise of prosecutorial discretion.’ ”

At issue is a statute the Justice Department has employed against at least 235 defendants accused of corruptly disrupting Congress’s certification of the 2020 electoral-college vote.

Many have argued that President Donald Trump's efforts amounted to an attempted coup on Jan. 6. Was it? And why does that matter? (Monica Rodman, Sarah Hashemi/The Washington Post)

Prosecutors have brought the obstruction charge in many of the most notorious cases, including against members of the Oath Keepers, Proud Boys and Three Percenters groups who allegedly conspired and prepared in advance for violence. The government has also leveled the charge against scores of individuals not accused of attacking police or destroying property but facing some of the most egregious allegations — such as occupying the Senate chamber, sitting in the vice president’s chair and targeting government officials.

Prosecutors have sought to distinguish such acts from protest-related civil disobedience that rarely results in prison time and more politically charged offenses such as sedition.

However, defendants in at least eight cases have moved to dismiss the count. They assert that the joint House and Senate session that met Jan. 6 does not qualify as an official proceeding of Congress; that the law is unconstitutionally vague on its face or as applied; or that it does not cover individuals’ alleged illegal actions, among other things.

The challenges rejoin a long-standing debate over what Congress meant when it overhauled an obstruction-of-justice statute in 2002, when as part of the ­Sarbanes-Oxley corporate responsibility act it broadly expanded a provision to cover “whoever corruptly . . . obstructs, in­fluences, or impedes any official proceeding.”

The Justice Department has argued that Congress intended a broad “catchall” provision for obstructive acts, passing Sarbanes-Oxley after a corporate fraud crisis wiped out hundreds of billions of dollars of shareholder value, including the early-2000s collapse of Enron Corp. and accounting giant Arthur Andersen.

Congress’s whole point in enacting such general clauses is to cover “matters not specifically contemplated,” because lawmakers do “not know what inventive criminal minds” might come up with in the future, Assistant U.S. Attorney Jeffrey S. Nestler said in the hearing Wednesday.

But some legal scholars question whether the expansion applies only to financial fraud or to traditional ­obstruction-of-justice crimes such as destroying documents.

As U.S. District Judge Randolph D. Moss did last month, Mehta noted that the Supreme Court in 2015 rejected an ­expansive reading of a related law, tossing the conviction of a Florida fisherman who destroyed ­smaller-than-20-inch red grouper to impede U.S. wildlife inspectors. The court ruled that when Congress barred the destruction of any “tangible object,” it meant documentary evidence, not fish.

“It seems to me — and I say this after having thought about this a fair amount — this statute potentially suffers from the same problems,” Mehta said.

Mehta, who was appointed to the U.S. District Court for the District of Columbia in 2014, said he could easily follow the high court’s plurality opinion and toss out the charge. Like Moss, Mehta said the government must be able to put individuals clearly on notice how “corruptly” obstructing or influencing Congress differs from ordinary trespassing, parading or disorderly conduct in the Capitol — lesser charges that are punishable by no more than six months in prison.

“The million-dollar question is: What’s the limiting principle?” Mehta said, suggesting the statute “clearly brings in innocent conduct,” encompassing anyone seeking to influence Congress.

Nestler cited two — that the statute targets only those who act “corruptly,” which he argued is an established question for juries to decide, and actions with a “nexus” or tie to a defined proceeding.

Nestler agreed that it is not a crime punishable by up to 20 years to stand and shout “Stop this proceeding!” at a congressional confirmation hearing — but argued that it is if one adds, “There’s a bomb under your chairs!”

“The objective here was not just to halt proceedings. The objective here was to scare Congress into halting proceedings,” Nestler said, likening the act to obstructing justice by raiding a courthouse or courtroom and forcing judges and jurors to flee a trial.

Still, Mehta protested, “Scaring the daylights out of everyone in the House or Senate . . . to me is very different than destroying evidence or intimidating witnesses.”

“That’s what the government intends to prove at trial,” Nestler replied, that these defendants acted corruptly “because they intended to intimidate Congress.”

Defense attorney David Fischer, arguing for Navy veteran Thomas Caldwell of Berryville, Va., objected that interrupting an electoral-vote certification was different from obstructing justice.

“It would be like someone interrupting a congressional declaration of war,” Fischer said. “That’s a very serious event, but it’s not obstruction of justice.”

Attorney Carmen D. Hernandez, defending Donovan Crowl, a member of a self-styled militia group in Ohio, argued that if the government’s “catchall” interpretation of the law were correct, “that’s the only statute you would need for obstruction.”

Moss and Mehta are the only judges who have heard arguments on the question, promising to rule quickly after receiving additional briefings over the next month. Near the end of Wednesday’s two-hour argument, Mehta concluded, “I don’t want this to sit very long.”

At the outset of Wednesday’s hearing, defense attorney Bradford Geyer of New Jersey said he had been retained by the family of one of the co-defendants, Army veteran Kenneth Harrelson of Brevard County, Fla., to replace John M. Pierce, an attorney who represents 17 riot defendants but who had not been appearing in court. His associates at one point said he had contracted the coronavirus.

Pierce reemerged an hour before the Oath Keepers hearing in another case, however, filing a notice in Harrelson’s case explaining that he had been incommunicado since Aug. 23 because he had spent 12 days in the hospital before being released Sunday. Pierce did not elaborate on why he was hospitalized and said he expects to be “fully operational next week.”

“I was not ‘missing’ or anything of the sort,” Pierce wrote.

Geyer said that he did not know and has not spoken with Pierce nor anyone he worked with and that the Harrelsons told him to go forward as best he could.