With the first trials connected to the Jan. 6 attack on the Capitol set to begin early next year, defense lawyers have started in earnest to road test strategies for defeating the government’s charges.

Some, in the most complicated cases, will most likely challenge the allegation that an organized conspiracy to storm the building predated any violence. Others, looking to offload the blame their clients face, may contend that they were authorized by President Donald J. Trump to take part in the attack.

But one group of lawyers representing those accused of assaulting the police is planning to make a more audacious — and more difficult — legal claim: They say they intend to argue that the officers themselves used excessive force on Jan. 6 and that their clients merely responded, acting in defense of other people or in their own defense.

This approach, while in its early stages, has gathered steam in recent weeks as defense lawyers have made their way through thousands of hours of videos of the Capitol attack, some of which, they say, show acts of brutality by officers. The videos, which are not yet public, may be released at upcoming hearings and, the lawyers say, will reveal scenes of violence not only by the rioters but also by police.

Though often hard to prove, self-defense claims have figured prominently in two high-profile recent cases with varying levels of effectiveness. Last month, a jury in Wisconsin rendered a verdict showing it believed Kyle Rittenhouse’s claims of self-defense and acquitted him of all charges connected to the fatal shootings of two men and the wounding of another during a violent confrontation on the streets of Kenosha in August 2020. A few days later, a Georgia jury rejected the self-defense arguments of three men charged with murdering Ahmaud Arbery and found them guilty.

At this point, about a half-dozen Jan. 6 defendants have signaled that they intend to mount a case that is based on self-defense or on the defense of others.

On Thursday, for example, a lawyer for Thomas Webster, a former New York City police officer charged with assault, indicated that he was inclined to pursue a self-defense case and argue that officers at the Capitol struck first. That same day, prosecutors filed papers in the case of Robert Gieswein, a militia member from Colorado, asking a judge to bar all self-defense claims at a trial set for February, suggesting that they believed Mr. Gieswein might raise them.

Any defendant who argues self-defense — or defense of others — will most likely to face an uphill battle. Already, judges and prosecutors have looked askance at the claims, with prosecutors in one case noting in court papers they were “simply not credible.”

Indeed, in order for such defenses to be viable, the rioters will have to persuade a judge and jury that they or others in the mob at the Capitol were victims of unlawful attacks by the police. That could be difficult given that so much of the rioters’ own violent behavior was caught on video and that officers are justified in using some amount of force in the performance of their jobs.

Most of the defendants mulling self-defense claims were involved in the ferocious melee at the Lower West Terrace of the Capitol, where the fighting was worse than anywhere else on Jan. 6 and often resembled a kind of medieval warfare. For nearly three hours, officers there were engaged in hand-to-hand combat with rioters, some of them carrying flag poles, hockey sticks, bear spray and batons.

The first person to have said he would pursue a self-defense case was Edward Jacob Lang, a self-described social media influencer from New York. He has been charged with seven counts of assaulting officers, some with a riot shield and others with a baseball bat.

In court papers filed by his lawyer, Stephen Metcalf, Mr. Lang said he became violent only after seeing several women in the mob being attacked by the police, including Rosanne Boyland, a Trump supporter who ultimately died. Mr. Lang has claimed that he tried unsuccessfully to save Ms. Boyland and has also said that he pulled another protester, Philip Anderson, to safety after he was sprayed by officers with an unknown orange gas that stopped his breathing.

“The police were heartlessly pushing people on top of each other creating this dogpile effect,” Mr. Lang said in a brief interview from a jail in Washington this month, “and people ended up dying.”

A few weeks ago, Ryan Nichols, a former Marine from Texas, also asserted that he was acting in self-defense and in defense of others when he assaulted the police. In his own court papers, Mr. Nichols described a horrific scene inside a tunnel at the Lower West Terrace where tear gas filled the air and screaming rioters were being crushed.

The papers describe a video that purports to show an officer in a white shirt in the crowd near Mr. Nichols beating one man with his collapsible baton and then turning his attention to a middle-aged woman in a MAGA hat to “pulverize her,” as Mr. Nichols’ lawyer, Joseph McBride, wrote. Over the course of four or five minutes, according to the description of the video, the white-shirted officer appears to strike the woman multiple times until blood spurts from her face and she collapses.

Last week, the government countered Mr. Nichols’ claims, saying that other video evidence shows that he was not near the white-shirted officer and thus was not in a position to observe — or be triggered by — any attack against the woman in question. The prosecutors argued that Mr. Nichols’ attempt to “cast himself as a hero who was merely fighting back against officers who were ‘terrorizing’ civilians” was preposterous.

Mr. Lang’s claims have been met with equal skepticism.

At a hearing in September, Judge Carl J. Nichols pointed out that even after Jan. 6, Mr. Lang was still using violent language. Judge Nichols noted, for example, that in messages sent to an unknown associate, Mr. Lang wrote that he was getting “an arsenal together” for President Biden’s inauguration, adding, “This is war.”

Despite the fact that some officers in the crowd on Jan. 6 may have acted roughly, Judge Nichols went on, Mr. Lang was in the mob sparring with them for more than an hour before he sought to help Ms. Boyland or Mr. Anderson. That seemed to cut against the idea that he was helping others.

“I do not find this argument particularly persuasive,” Judge Nichols said.