The idea is that, because of Mueller’s findings about collusion, prosecutors could not argue that Trump acted corruptly to hide an underlying crime.

Legal experts say the fact that special counsel Robert Mueller did not find that President Trump and his associates and the Russian government colluded to interfere in the 2016 election appears to have been a major factor in Attorney General William Barr’s decision not to charge Trump with obstruction of justice.

No collusion? No obstruction. That’s what Attorney General William Barr appears to believe, at least in part.

The problem for prosecutors would be that “you can’t prove that there was any reason to obstruct justice. Because you don’t have collusion, then the linkage to obstruction is just not there,” said Wayne State Law School Professor Peter J. Henning.


“Proving a case would be very difficult,” he said. “You have to find a motive. Was there a good reason for the person to try to stymie an investigation?”

Barr said in his memo that he and Deputy Attorney General Rod Rosenstein had noted, in making their decision not to charge Trump with obstruction, that Mueller had found “the evidence does not establish that the President was involved in an underlying crime related to Russian election interference.”

“While not determinative, the absence of such evidence bears upon the President’s intent with respect to obstruction,” Barr observed. He went on to say that a “corrupt intent” was one of the necessary elements for an obstruction of justice charge.

“I think he is saying that the fact that there are no underlying substantive criminal charges makes it more difficult to prove the elements of an obstruction charge, and that’s true. Obstruction cases are famously hard to prove, both as a legal matter and to a jury,” Harvard Law Professor Alex Whiting, a former federal prosecutor, said in an e-mail.


Whiting said that whether to bring obstruction charges is “often a judgment call. We haven’t seen the facts in the Mueller report, but I suspect that an aggressive prosecutor might be able to mount a case, while a more cautious one would hesitate. There will be debate about Barr’s judgment once the facts become known, but the reality is that these obstruction cases are difficult.”

Henning said, “Obstruction of justice is not an easy crime to prove. No one should be surprised that Barr said there’s no criminal activity here. ... Saying that we don’t find any obstruction of justice is actually a fairly easy thing for a prosecutor to do.”

Barr appeared to foreshadow his actions in a controversial memo critical of the Mueller investigation that he sent in June 2018 to the Justice Department as a private lawyer.

Barr, who had previously served as attorney general under George H.W. Bush, was grilled about the letter months later during his confirmation hearing, with a top Democrat questioning whether he had written it to ingratiate himself with the president.

Barr said in the letter that, in his opinion, Mueller’s obstruction of justice investigation was “fatally misconceived” and based on “a novel and legally insupportable reading of the law.” His general argument was that, in the case of the firing of former FBI director James Comey, a president shouldn’t be charged for trying to direct investigations, including investigations targeting the president. (A number of legal experts have disagreed.)


But he also argued in the letter that, in the case of Trump’s firing of Comey and his alleged request to Comey to go easy on an investigation of former national security adviser Michael Flynn, “even if one were to indulge Mueller’s obstruction theory … the President’s motive … could not have been ‘corrupt’ unless the President and his campaign were actually guilty of illegal collusion.”

He said the obstruction charge would be “entirely dependent on first finding collusion.”

“Until Mueller can show that there was unlawful collusion, he cannot show that the President had an improper ‘cover up’ motive,” he wrote. “Either the President and his campaign engaged in illegal collusion or they did not. If they did, then the issue of ‘obstruction’ is a sideshow. However, if they did not, the cover up theory is untenable.”

The Mueller investigation had gripped the nation with the spectacle of a respected lawman probing the actions of a scandal-plagued president. Mueller submitted his final report to the Justice Department on Friday and Barr sent a letter outlining its “principal conclusions” — and his decision not to prosecute — to Congress on Sunday.

The release of Barr’s letter continued to reverberate on Monday. Congressional Democrats, who are undertaking their own investigations of collusion and obstruction, clamored for the Justice Department to release the entire report from Mueller, not just Barr’s summary. Trump said releasing it “wouldn’t bother me at all.” He also claimed total vindication and said the investigation had been “a terrible thing.”


Material from Globe wire services was used in this report.