WASHINGTON — After an extraordinary public campaign by President Trump and his allies, the Justice Department dropped its criminal case on Thursday against Michael T. Flynn, Mr. Trump’s first national security adviser.
Mr. Flynn had previously pleaded guilty twice to lying to F.B.I. agents about his conversations with a Russian diplomat during the presidential transition in late 2016.
The move was the latest example of Attorney General William P. Barr’s efforts to chisel away at the results of the Russia investigation. Documents that Mr. Flynn’s lawyers cited as evidence of prosecutorial misconduct were turned over as part a review by an outside prosecutor whom Mr. Barr assigned to re-examine the case. Mr. Barr has cast doubt not only on some of the prosecutions in the Russia investigation but also on the premise itself, assigning another independent prosecutor to scrutinize its origins.
The decision for the government to throw out a case after a defendant had already pleaded guilty was also highly unusual. It undoes what had been one of the first significant acts of the special counsel investigation into possible ties between the Trump campaign and Russia’s 2016 election interference — the prosecution of a retired top Army general turned national security adviser who pleaded guilty to lying to investigators.
Though Mr. Trump fired Mr. Flynn weeks into his presidency for lying to Vice President Mike Pence about the conversations with the diplomat, he has long complained that a corrupt few at the F.B.I. mistreated Mr. Flynn and suggested he might pardon him. Law enforcement officials moving to drop the charges took issue in a court filing with the questioning of Mr. Flynn in January 2017 as part of the Russia investigation that Mr. Mueller later took over.
The questioning “was untethered to, and unjustified by, the F.B.I.’s counterintelligence investigation into Mr. Flynn,” the acting United States attorney in Washington, Timothy Shea, wrote in a motion to dismiss the charges. Prosecutors said that the case did not meet the legal standard that Mr. Flynn’s lies be “materially” relevant to the matter under investigation.
“The government is not persuaded that the Jan. 24, 2017, interview was conducted with a legitimate investigative basis and therefore does not believe Mr. Flynn’s statements were material even if untrue,” Mr. Shea wrote.
Democrats condemned the move. “A politicized and thoroughly corrupt Department of Justice is going to let the president’s crony simply walk away,” said Representative Jerrold Nadler, Democrat of New York and the chairman of the House Judiciary Committee. “Americans are right to be furious and worried about the continued erosion of our rule of law.”
He said he would ask the Justice Department inspector general to investigate the dropped charges and work to secure Mr. Barr’s testimony before his committee as soon as possible.
In dropping the charges, law enforcement officials abandoned the stance of prosecutors who had been on the case, who had argued that Mr. Flynn’s conversations with the Russian ambassador to the United States at the time, Sergey I. Kislyak, “went to the heart” of the F.B.I. investigation.
Mr. Trump told reporters on Thursday that Mr. Flynn was “an innocent man” and accused Obama administration officials of targeting him to try to “take down a president.” He angrily tore into his unnamed persecutors. “I hope a lot of people are going to pay a big price because they’re dishonest, crooked people,” Mr. Trump said. “They’re scum — and I say it a lot, they’re scum, they’re human scum. This should never have happened in this country.”
The Justice Department said that it did not brief the White House before it dropped the charges.
“I want to make sure that we restore confidence in the system,” Mr. Barr said in an interview with CBS News. “I believe that justice in this case requires dismissing the charges against General Flynn.”
When asked whether Mr. Flynn lied, Mr. Barr said that “people sometimes plead to things that turn out not to be crimes.”
Sidney Powell, Mr. Flynn’s lawyer, said on the Fox Business Network that she and her client were “relieved and gratified” that Mr. Barr withdrew the case. She called the decision “a restoration of the rule of law.”
Mr. Flynn pleaded guilty in December 2017 to lying to the F.B.I. about his conversations with Mr. Kislyak during the presidential transition. He had also entered a guilty plea a second time in 2018 at an aborted sentencing hearing. At the time, Mr. Flynn said he knew that lying to the F.B.I. was a crime and accepted full responsibility for what he had done.
The climactic move by the Justice Department appeared to be brewing in recent days after the outside prosecutors reviewing the case said they had found new documents that were possibly exculpatory, raising the hopes of Mr. Flynn’s lawyers and vocal supporters that the former general would be exonerated.
One of the documents showed the F.B.I. was on the verge of closing a counterintelligence investigation into Mr. Flynn’s ties to Russia in early January 2017. Mr. Shea, a longtime trusted adviser of Mr. Barr’s, said in the court filing that F.B.I. agents had no reason to interview Mr. Flynn at the White House weeks later.
In a possible sign of disagreement, Brandon L. Van Grack, the Justice Department lawyer who led the prosecution of Mr. Flynn, abruptly withdrew from the case on Thursday. Mr. Flynn’s lawyers have repeatedly attacked Mr. Van Grack by name in court filings, citing his “incredible malfeasance.” Other prosecutors in Mr. Shea’s office were stunned by the decision to drop the case, according to a person who spoke with several lawyers in the office.
It is now up to the federal judge in Washington overseeing the case, Emmet G. Sullivan, to decide whether to dismiss it and close off the possibility that Mr. Flynn could be tried again for the same crime. If the judge wants, he could ask for written submissions and hold a hearing on that topic.
Judge Sullivan, who accepted Mr. Flynn’s original guilty plea, could also weigh in on whether he believes any of the new materials that the government has produced to Mr. Flynn’s lawyers represent any violation on the part of the Justice Department or its lawyers who worked on the case.
The White House was prepared for the possibility of Mr. Trump pardoning Mr. Flynn last week, according to two people familiar with the discussions. But some advisers urged the president to hold off and let the case play out, either with the Justice Department or with the judge, according to the people familiar with the discussions.
So Mr. Trump held off.
Mr. Flynn, a decorated lieutenant general and former head of the Defense Intelligence Agency, was an early supporter of Mr. Trump’s 2016 presidential campaign, joining the crowd in a “lock her up” chant about Hillary Clinton, then the presumptive Democratic presidential nominee, at the Republican National Convention that year.
After winning election, Mr. Trump named Mr. Flynn his national security adviser. In late December 2016, Mr. Flynn and Mr. Kislyak spoke shortly after the Obama administration placed sanctions on Russia for interfering in the election, and Mr. Flynn advised that the Russians hold off on escalating in response, undermining that administration’s foreign policy.
The F.B.I. had been close to closing its inquiry into Mr. Flynn. But as investigators discovered the conversations in early January through routine government wiretaps of Mr. Kislyak, and as they learned in subsequent days that he had lied to other White House officials about them, they began to conclude that they had reason to suspect that Mr. Flynn constituted a national security threat.
Law enforcement officials warned the White House that Russia could have blackmailed Mr. Flynn, then the Trump administration’s highest-ranking national security official. But seeing no move by Mr. Trump to address the issue, F.B.I. agents decided to question Mr. Flynn, where he repeatedly lied about his talks with Mr. Kislyak.
But Mr. Shea wrote in asking Judge Sullivan to dismiss the charges that the F.B.I. should never have interviewed Mr. Flynn. Agents had no need to speak with him because the investigation was on the verge of closing and the F.B.I. knew what was said on the call because agents had transcripts.
Mr. Shea also dismissed F.B.I. concerns about Mr. Flynn having lied about the conversations about sanctions on Russia to Mr. Pence and to a White House spokesman at the time, Sean Spicer, who both provided misinformation to the public. In his filing, Mr. Shea said their statements did not “provide a separate or distinct basis for an investigation.”
He added that if F.B.I. officials were so worried, they should have talked with Mr. Pence and Mr. Spicer directly.
“The frail and shifting justifications for its ongoing probe of Mr. Flynn, as well as the irregular procedure that preceded his interview, suggests that the F.B.I. was eager to interview Mr. Flynn irrespective of any underlying investigation,” Mr. Shea wrote.
Mr. Shea also said the government could not prove its case at any trial.
“Moreover, we do not believe that the government can prove either the relevant false statements or their materiality beyond a reasonable doubt,” and “even if they could be material, the government does not believe it could prove that Mr. Flynn knowingly and willfully made a false statement beyond a reasonable doubt.”
The admission was striking because when agents interviewed Mr. Flynn, prosecutors said they gave him repeated opportunities to correct his misstatements. Judge Sullivan had also previously said Mr. Flynn’s statements were material to the Russia inquiry.
In earlier court filings, Mr. Van Grack said that the “topics of sanctions went to the heart of the F.B.I.’s counterintelligence investigation.”
He also said that “any effort to undermine those sanctions could have been evidence of links or coordination between the Trump campaign and Russia.”
Mr. Flynn cooperated extensively before moving this year to withdraw his plea and fight the case in court. The special counsel’s prosecutors considered Mr. Flynn a key early cooperator as “one of the few people with long-term and firsthand insight” into their inquiry into whether any Trump associates criminally conspired with Russia’s 2016 election interference.
Michael Crowley contributed reporting from Washington, and Maggie Haberman from New York.