WASHINGTON — A federal judge on Monday rebuffed accusations by President Trump’s first national security adviser, Michael T. Flynn, that F.B.I. agents and federal prosecutors engaged in misconduct in his criminal case, delivering a comprehensive rebuke to his 11th-hour claims.
The 92-page ruling by Judge Emmet G. Sullivan also effectively ended Mr. Flynn’s hopes that the judge would toss his conviction as prosecutors consider whether to ask for prison time for Mr. Flynn. It was also a blow to supporters of Mr. Flynn, who have amplified a false narrative that he was framed in a plot by the so-called deep state to sabotage Mr. Trump.
Judge Sullivan set sentencing for Jan. 28. Mr. Flynn, a retired Army lieutenant general, agreed in late 2017 to plead guilty to lying to F.B.I. agents in the Russia investigation in exchange for cooperating with investigators. But he has increasingly adopted a combative stance, including replacing his lawyer with a prominent critic of the special counsel’s investigation, which culminated in his request that Judge Sullivan throw out the case altogether.
In an exhaustive decision, Judge Sullivan doused the incendiary claims of Mr. Flynn’s lawyers, who were led by Sidney Powell, a former federal prosecutor who hawks anti-special-counsel T-shirts on her website. Ms. Powell began representing Mr. Flynn in June, gambling on a risky legal strategy, and requesting dozens of pieces of information from the government that she said would exonerate her client. She also asked the judge to hold prosecutors in contempt.
Among other things, Ms. Powell asked for material that appeared to be based on claims about the Russia investigation that have circulated in the conservative media without evidence to back them up. For example, she suggested that a former top F.B.I. official, Andrew G. McCabe, declared that the bureau would go after Mr. Flynn and then Mr. Trump. (Prosecutors said they had disproved the allegation, which an agent called “ludicrous.”)
One by one, Judge Sullivan rejected her assertions.
For instance, she wrote that the government suppressed evidence favorable to Mr. Flynn related to agents’ questioning of him. “High-ranking F.B.I. officials orchestrated an ambush interview,” Mr. Flynn’s lawyers wrote in court documents, saying they were “trapping him into making false statements they could allege as false.”
Judge Sullivan dismissed that accusation, citing agents’ notes and F.B.I. memos known as 302s documenting their interview of Mr. Flynn. The documents were “both consistent and clear that Mr. Flynn made false statements to the F.B.I.,” Judge Sullivan wrote.
In other requests, Mr. Flynn’s lawyers sought material that they already had or that seemingly had little or nothing to do with his case. Judge Sullivan sided with prosecutors who said in several instances that Mr. Flynn’s lawyers wanted information that would not help their client. “By any conceivable measure, Mr. Flynn’s requested information is neither helpful nor relevant to the defense,” the judge wrote.
Prosecutors had previously said that some of Ms. Powell’s contentions were “divorced from the facts” or that she was relying on conspiracy theories in “demanding that the government engage in a fishing expedition for documents that could offer support for those theories.”
The judge also expressed ethical concerns about a filing by Mr. Flynn’s lawyers, saying they “lifted verbatim portions from a source without attribution,” only citing in a footnote a brief in a separate case.
Additionally, Mr. Flynn has pleaded guilty twice in the case, not only in 2017 but also a year ago at an initial sentencing hearing. Judge Sullivan had presaged his ruling when he chastised Mr. Flynn during that hearing for suggesting the F.B.I. had duped him into lying to the agents who questioned him.
To maximize his cooperation agreement with prosecutors, Mr. Flynn delayed his sentencing at the time to testify for the government against a former business partner, Bijan Kian.
But Mr. Flynn changed his story on the eve of Mr. Kian’s trial, and prosecutors decided against calling Mr. Flynn as a witness in the trial. Mr. Kian was convicted in July, but a judge later overturned the charges, saying the government had failed to present enough evidence to sustain their charges that he had secretly lobbied on behalf of Turkey.
Prosecutors in Mr. Flynn’s case have suggested they might change their stance on his punishment; they have said he deserves little to no prison time. Judge Sullivan directed them to file a sentencing memo in coming weeks.
The judge had originally set a sentencing date for this week, but both sides agreed to a further delay until the Justice Department inspector general delivered a highly anticipated report on aspects of the Russia investigation. The report was released last week and revealed problems with the F.B.I.’s investigation of another Trump associate, the former campaign adviser Carter Page.
Ms. Powell had suggested that the report would include revelations favorable to her client. “The evidence we presented is overwhelming that they have been hiding the ball all along,” she said recently on a pro-Trump television network, One America News Network.
That did not happen. In fact, the inspector general said that the F.B.I. had sufficient information to investigate Mr. Flynn.