In summarizing Special Counsel Robert Mueller’s report on Russian election interference, Attorney General Bill Barr said there were two major questions the investigation examined: whether there was coordination or collusion between the Trump campaign and the Russian government, and whether President Donald Trump sought to obstruct justice. The report did not establish coordination or collusion.

That lack of proof on collusion is one of the reasons for not pursuing an obstruction-of-justice prosecution, Barr said: There was no underlying crime from Russia connections for Trump to cover up.

While Barr said this wasn’t the only factor that played into the decision about whether to prosecute, he explicitly cited it as one of them.

In the 24 hours after the Barr letter was released, we noticed a lot of cable TV debate about whether someone can or can’t be tried for obstructing justice if there is no underlying crime. Put another way, can you obstruct justice if there was theoretically nothing to obstruct? We decided to take a closer look.

We checked with 11 legal experts to nail down answers. Essentially all of these experts agreed that obstruction can indeed be prosecuted without an underlying crime — and has been in the past, notably in the case of Martha Stewart.

Several experts added, however, that there are some important distinctions between these historical precedents and what Mueller found. So the debate (sorry) will likely continue.

What Barr wrote

What is obstruction of justice? It refers to "interference with the orderly administration of law and justice," including "proceedings before departments, agencies, and committees." The relevant type in the Trump example is likely "obstruction of criminal investigations."

Three elements are generally required for a conviction on obstruction of justice: the existence of a pending federal judicial proceeding; the defendant’s knowledge of this proceeding; and the defendant’s corrupt intent to interfere with, or attempt to interfere with, the proceeding.

Ultimately, Barr and Rosenstein determined that the three elements that are required to prove obstruction were not met.

Barr wrote that in making a determination not to prosecute for obstruction, he considered that evidence did not establish that the president was involved in an underlying crime.

Furthermore, according to Barr’s letter, the Special Counsel "did not draw a conclusion one way or the other as to whether the examined conduct constituted obstruction. Instead, for each of the relevant actions investigated, the report sets out evidence on both sides of the question and leaves unresolved what the Special Counsel views as ‘difficult issues’ of law and fact concerning whether the President’s actions and intent could be viewed as obstruction. The Special Counsel states that ‘while this report does not conclude that the President committed a crime, it also does not exonerate him.’ "

Until the full text of the Mueller report is released — and possibly not even then, depending on what it includes — we won’t know which of the three elements of obstruction, if any, would have been provable.

Obstruction of a non-crime?

Legal experts told us that a president (or anyone) could still be prosecuted for obstructing justice if they believed they might be prosecuted — even if they ultimately never are.

"You can obstruct justice even if a prosecutor ultimately finds you were not guilty of committing the crime that was the focus of the underlying investigation," said Miriam Baer, a professor at Brooklyn Law School. "Even if a prosecutor ultimately concluded that you weren’t guilty of crime X, that says nothing as to whether you thought that you might be indicted for crime X, or, for that matter, if you thought one of your friends of family members would be indicted for crime X."

Eric Posner, a professor at the University of Chicago Law School, agreed that an obstruction prosecution could have been argued in this case.

"Suppose Trump knew that no crime had been committed but believed that the investigation would uncover politically or personally embarrassing information, or if he believed that the investigation would embarrass or implicate an ally, aide, or family member," Posner said. "Then interfering with the investigation is a crime. The reason is that the purpose of the investigation is to find the truth, and if people obstruct an investigation, then the investigation becomes more difficult, wasting government resources."

That said, an obstruction case is naturally going to be stronger if there is an underlying crime that’s being prosecuted, said Ric Simmons, a professor at the Ohio State University Moritz College of Law.

It is "technically possible, but the legal and practical challenges in winning such an obstruction case would be great," Simmons said. "A prosecutor would have to prove that the president believed there was a collusion case ‘contemplated’ against him even when he did not engage in collusion. That is theoretically possible, but hard to prove to a jury."

The cases of Stewart and Libby

The highest-profile example of trying a case of obstruction without an underlying crime that our experts could think of was the prosecution of Martha Stewart, the founder of a popular lifestyle and media company. Stewart was tried on charges related to her sale of 4,000 shares of ImClone, a pharmaceutical company, one day before the company’s stock price plummeted.

The charges of securities fraud were thrown out, but prosecutors persisted with charges of obstruction of justice and lying to investigators. She was found guilty of four counts and in 2004 was sentenced to five months of prison, five months of house arrest, and two years of probation.

Stewart "surely feared reputational and business harm" even in the absence of a crime, said Robert Weisberg, co-director of Stanford University’s Criminal Justice Center.

Another notable example is the case of Scooter Libby, a former top aide to Vice President Dick Cheney, said Samuel Buell, a law professor at Duke University. Libby was charged by a special prosecutor with obstruction, perjury and false statements, but not any underlying crime related to the outing of a CIA employee, Valerie Plame. (Trump pardoned Libby.)

What about Watergate?

Legal experts said there are echoes of Watergate in the current situation.

James D. Robenalt, an attorney with the firm Thompson Hine LLP and creator of a continuing legal education class on Watergate, said the parallels are striking.

President Richard Nixon "knew nothing about the break-in at the Democratic National Committee before the Committee to Re-Elect the President caused it to happen, and the White House — but for one, maybe two tangential people — did not know about the crime." So Nixon could not have been prosecuted for the break-in, nor could other key White House officials, he said. Yet "they all covered up and obstructed justice to protect the Committee to Re-Elect the President," Robenalt said.

But some legal scholars see the Trump example as murkier.

In the Watergate case, "there was clearly a crime that Nixon knew about, whereas in the Trump example, there is little to no basis for charging a crime of collusion — at least according to Barr’s summary," said Christopher Slobogin, director of the criminal justice program at Vanderbilt University. "Thus Trump can more credibly say that his actions were not motivated by worry about such a charge."

Stephen B. Presser, a Northwestern University law professor and a visiting scholar in conservative thought and policy at the University of Colorado-Boulder, agreed that there’s a distinction between the two cases.

"As I read Barr's letter he's focused on motive to conceal clear misconduct, which I think is entirely appropriate," Presser said. "Richard Nixon knew that the break-in at the Watergate was wrong, and sought to conceal evidence of that."