President Donald Trump. Credit: Shealah Craighead / White House

The federal investigation into Russia's interference in the U.S. presidential election and what the Trump campaign team knew, or didn't know, is sure to stretch for weeks—if not many more months. That could be unsettling for anyone who might be in the orbit of Robert Mueller and his special counsel's office prosecutors.

President Donald Trump has told associates, according to a CNN report, that he expects some sort of all-clear from Mueller, something he can show off that says he has done nothing wrong. CNN characterized this document as a “letter of exoneration.”

But Trump may not want to get his hopes up. Several white-collar defense lawyers in Washington said it would be outside the typical course of things for a prosecutor to put anything in writing that would absolve someone of any wrongdoing.

“That's just not normal procedure whatsoever,” said Mayer Brown partner Kelly Kramer, co-leader of the firm's white-collar defense and compliance practice. He added: “I've never heard of an exoneration letter. The only way I can see to get to 'exoneration' here is through a report to Congress, which of course is not typically how the DOJ does business.”

Federal prosecutors have discretion to write a “declination” memo that tells a target he or she is no longer under investigation, or that the investigation has closed. But these memos are rare, and there's nothing that compels a prosecutor to write one in the first place, several white-collar defense lawyers said.

In some cases, an individual or company will learn through an informal call that an investigation has been closed. Sometimes, that notification will never come.

“Silence is golden,” said one lawyer.

Declination memos, when they do get sent, come in a matter-of-fact style. They give the status of an investigation without going so far as to assert a onetime target is innocent. Several lawyers said they've never seen a declination memo longer than a single page.

”Exoneration is not a concept that exists in the panoply of weapons and communications from the Department of Justice,” said Gibson, Dunn & Crutcher partner Joel M. Cohen, a former federal prosecutor who is now co-leader of his firm's white-collar and investigations group. “You can only be exonerated after you've been charged. A prosecution team, they don't exonerate people.”

Declination letters from a prosecutor, Cohen said, let the target know “we decline to prosecute you. They typically also have a caveat that this has no legal consequence, and that they reserve the right to reverse their stance if new evidence changes their assessment.”

A lawyer for Trump declined to comment Tuesday.

Prosecutors, of course, don't always bring criminal cases against targets of an investigation. There are any number of reasons for this. Witnesses might not fully cooperate. The evidence just might not be there. “What has been shown is no collusion. No collusion. There has been absolutely no collusion,” Trump told reporters this month.

Sometimes, a federal grand jury—perhaps not sold on the day's ham sandwich—decides not to indict. In that case, any would-be defendant could wave around a copy of the “no bill.”

The U.S. Justice Department publicly posts some of its declination memos concerning companies that were under investigation for possible foreign-bribery violations.

These memos are not highly detailed recitations of the facts—and, anyway, they do in some instances reveal criminal activity. The public availability of Foreign Corrupt Practices Act declination memos gives companies some thinking about effective compliance programs and how much goodwill cooperation might engender.

Mueller might have reasons for a detailed or less detailed memo, if he sends one at all—to anyone. But that memo almost certainly would not “exonerate” the target or otherwise declare innocence.

Even juries don't do that. You're either guilty or not guilty. They don't say you are innocent.

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