Donald Trump may have been telling his supporters he wanted them “to do something more” than simply protest his defeat to Joe Biden in the 2020 presidential race when he told a mob of them to “fight like hell” on the day of the deadly Capitol attack on 6 January 2021, according to findings from a federal judge on Wednesday.

The opinion from judge John Bates came in the form of a ruling barring one man charged with having a hand in staging the Capitol assault that day – Alexander Sheppard – from arguing that Trump, as president at the time, had authorized his actions.

Bates’s judgment recounted how Trump’s speech near the White House on 6 January, the day that Congress certified his loss to Biden, urged his supporters to march to the Capitol without saying that it was illegal to enter the area where lawmakers would be voting.

“These words only encourage those at the rally to march to the Capitol … and do not address legality at all,” wrote Bates, who was appointed to Washington DC’s federal courthouse bench by former president George W Bush. “But, although his express words only mention walking down … to the Capitol, one might conclude that the context implies that he was urging protesters to do something more – perhaps to enter the Capitol building and stop the certification.”

Bates made it a point to note that his reasoning was not out of line with the final report recently issued by a congressional committee investigating the Capitol attack, which has been linked to nine deaths, including suicides of traumatized law enforcement officers who defended the building that day. That committee’s report found Trump acted “corruptly” on the day of the attack because he knew it was illegal to stop the certification of Biden’s victory over him, and the panel issued a non-binding recommendation for federal prosecutors to file criminal charges against the former president.

Bates added that he believed Trump’s use of the phrase “fight like hell” in his speech on 6 January – two weeks before Biden assumed control of the Oval Office – potentially served as “a signal to protesters that entering the Capitol and stopping the certification would be unlawful”.

“Even if protesters believed they were following orders, they were not misled about the legality of their actions and thus fall outside the scope of any public authority defense,” Bates wrote.

“The conclusions reached here … [are] consistent with the [January 6] committee’s findings.”

Sheppard is one of several Capitol attack defendants to try to argue that they were carrying out a president’s bidding that day, though that strategy hasn’t been a winning one in court. For example, after telling a jury that he went to the building on the day of the attack because he wanted Trump’s “approval” and because he believed he was obeying “presidential orders”, Capitol rioter Dustin Thompson was convicted and later sentenced to three years in prison.

It hasn’t been clear whether Trump might be charged with a role in the Capitol attack. Prosecutors have charged more than 900 other people, many of whom have already been convicted and sentenced to prison.

Bates’s judgment appears to be the first court ruling to cite the January 6 committee’s 800-page report since its publication last week.