Suspect Tries to Compare Capitol Riot to Last Year’s Violence in Portland, Ore.

The comparison has become a staple among right-wing figures in the news media and Republican politicians: The attack on the Capitol on Jan. 6 was really no different than the unrest last year that accompanied months of racial justice protests. Any discussion of the first should — out of fairness, they have said — make reference to the second.

Now, for the first time, a federal court is poised to consider the merits of that argument, albeit in a narrow legal context.

The move comes in the case of Garret Miller, a Dallas man charged with storming the Capitol and facing off with officers inside. Last month, Mr. Miller, 34, raised what is known as a selective prosecution defense, claiming that he had been charged with violent crimes because of his conservative beliefs while dozens of leftist activists in Portland, Ore., had similar charges stemming from last year’s violence reduced or dismissed.

“Mr. Miller has been treated differently by the government than the Portland rioters based upon the politics involved,” his lawyer wrote.

On Thursday, the government rebutted Mr. Miller’s claims, suggesting in court papers that a bright line stood between the nationwide protests last summer and the storming of the Capitol in January. While prosecutors acknowledged that those arrested during weeks of unrest at Portland’s federal courthouse had committed “serious offenses,” they insisted that the suspects in Washington were involved in “a singular and chilling event in U.S. history” that threatened not only the safety of the Capitol but also “democracy itself.”

While selective prosecution defenses rarely succeed, the government’s filing in Mr. Miller’s case was an unusual example in which the Justice Department opened a window on its decision-making process in the separate prosecutions, which right-leaning partisans have long sought to connect.

The attempt to equate the unrest in Portland with the later violence in Washington was critical, for example, in arguments by Republican senators for sinking a bipartisan, 9/11-style commission to examine the events of Jan. 6. The comparison was raised again this week by Republicans like Representative Jim Jordan of Ohio, who criticized the Democratic plan to investigate the Capitol assault with a select congressional committee.

“It’s important to point out that Democrats created this environment,” Mr. Jordan said, “sort of normalizing rioting, normalizing looting, normalizing anarchy, in the summer of 2020, and I think that’s an important piece of information to look into.”

Mr. Miller’s legal argument rests on an analysis of 74 criminal cases stemming from the courthouse attacks in Portland. In nearly 30 of those cases, prosecutors ultimately dropped the charges, according to his lawyer, F. Clinton Broden. In a dozen more cases, defendants were offered a dismissal upon completion of a pretrial diversion program. Three Portland defendants, Mr. Broden noted, were allowed by the government to plead guilty to “significantly reduced charges.”

The reason, Mr. Broden said, was politics.

“Most, if not all, of the Portland dismissals, offers of pretrial diversion, and pleas to significantly reduced charges came after a change from the Republican administration to the Democratic administration running the Department of Justice,” he wrote.

Prosecutors disputed Mr. Broden’s calculations as a preliminary matter, arguing that they contained “inaccuracies,” but the government’s filing also sought to make a broader point that there was more at stake in Washington on Jan. 6 than in weeks of turmoil in Portland.

Mr. Miller, prosecutors noted, was “part of a mob” that “breached the Capitol building, and assaulted law enforcement with the goal of impeding congressional certification of the 2020 presidential election.” The defendants in Portland, they pointed out, never actually broke into the courthouse and never disrupted a proceeding before Congress.

The prosecutors also argued that they have better evidence against Mr. Miller — and the hundreds of other rioters charged in connection with Jan. 6 — than they ever managed to obtain against the protesters in Portland.

In the days leading to the Capitol attack, court papers say, Mr. Miller posted messages on Facebook, talking about a potential civil war and the collapse of the economy, and suggesting that he might take firearms to Washington. On the day of the riot, the papers say, surveillance videos show him pushing past officers and entering the Capitol while others show him confronting the police inside in “a fighting stance with one of his legs in front of the other.”

Moreover, prosecutors say, in the days that followed the riot, Mr. Miller posted messages on Twitter threatening to “assassinate” Representative Alexandria Ocasio-Cortez, Democrat of New York. He is also accused of threatening the officer who fatally shot a woman, Ashli Babbit, in the Capitol by posting a photo of a noose on Instagram and writing, “He will swing.”

That kind of damning evidence tends not to exist in the Portland cases, prosecutors said. In those matters, they contend, the government’s proof was often based on police officers struggling to identify suspects “on a darkened plaza with throngs of people.” Evidence like that, they added, “could be challenged at trial,” offering a suggestion about why so many cases in the West have been dismissed.

Mr. Miller’s motion, which will be considered by Judge Carl J. Nichols of Federal District Court in Washington, was only the latest effort by a Capitol Hill defendant to attack the charges against him. Other defendants have challenged the applicability of certain statutes or have sought to move their trials out of Washington, arguing that local jurors are too liberal to give them fair trials.

But Mr. Miller’s selective prosecution claim is the first so far to accuse the government of blatantly playing politics in the Jan. 6 investigation — an accusation that prosecutors denied.

“Stripped to its core,” the prosecutors wrote, “Miller relies on rank conjecture in suggesting that political favoritism has guided the government’s charging and plea decisions.”