ARI SHAPIRO, HOST:

Now we're going to take a closer look at obstruction of justice and what it means if a sitting U.S. president is accused. Ryan Goodman is a professor of law at New York University and he joins us on the line from our New York bureau. Hi there.

RYAN GOODMAN: Hi, thanks for having me.

SHAPIRO: So as we've heard, the special counsel's reportedly looking into whether the president obstructed justice. First, remind us just what that phrase, obstruction of justice, means.

GOODMAN: So obstruction of justice, it's a federal criminal offense. And it basically means trying to somehow corruptly influence or subvert an ongoing investigation or something like a grand jury proceeding.

SHAPIRO: Now, typically, if a special counsel finds evidence that someone committed a crime they present that evidence to a grand jury, which hands up an indictment. Then there's a trial. What happens if the person accused of the crime is a sitting president?

GOODMAN: That's a great question. So there is a prevailing view that a sitting president is immune from criminal prosecution, meaning that the only option, really, is to go through an impeachment process in the Congress. But that's not a universally held view, so it's never been tested in court whether or not a sitting president is immune.

SHAPIRO: So that would ultimately have to be decided by the Supreme Court.

GOODMAN: That's correct. The Supreme Court almost decided the question with President Nixon. And in that case, the special prosecutor did file a brief with the Supreme Court saying that the president should not be immune. But they didn't decide the issue.

SHAPIRO: I was going to ask who would bring this case. It sounds like it would be the special prosecutor, in this case Robert Mueller.

GOODMAN: Exactly.

SHAPIRO: Would it make any difference if the crimes that he is accused of were committed before he took office or while he was in office?

GOODMAN: Not really because the point of the idea that the president is immune is that it is such a burden on the office of the presidency to be going through a criminal proceeding. That's one of the reasons why they're just kind of separate from it. But that also would mean, for example, after he stepped down - let's say after a four-year term - then he would be able to be prosecuted in those circumstances.

SHAPIRO: And so if a president is accused of wrongdoing while he's in office, you're saying that it's possible once he leaves office there could be a case brought in criminal court.

GOODMAN: That's right. Representative Ted Lieu tweeted - he kind of cheekily said it, but it was a good point. He said, statute of limitations for obstruction of justice is five years, everybody. Just remember that.

SHAPIRO: Now, in a typical criminal case, the indictment and trial are where the public can see the allegations laid out in full. If we're talking about a sitting president and there's not likely to be a criminal trial, and it's up to Congress whether or not to begin impeachment proceedings, when does the public get to see in full what it is that investigators found?

GOODMAN: So I suppose at the end of the day it's quite likely that the special counsel will, in fact, produce a report. And it would be a public report. There's, you know, an open question as to whether or not he would do it in one final report that has everything in it, and therefore we might be waiting a very long time. Or he could first introduce obstruction of justice and then separately keep going with the other investigations that he's handling, which is the much bigger investigation of Russian influence in the presidential campaign.

SHAPIRO: There are obviously instances where special counsel or special prosecutors have looked into presidents in the past, whether we're talking about Nixon or Clinton. How extraordinary is the situation that we're looking at today?

GOODMAN: It's unbelievably extraordinary. I mean, this could put us in a real crisis for our country. It's of an extraordinary nature that we have a special counsel even involved and, based on news reports, know today that he is investigating obstruction of justice, which means that the president himself is a target of that investigation.

SHAPIRO: Ryan Goodman, professor of law at New York University. Thanks for joining us.

GOODMAN: Thanks so much for having me. Transcript provided by NPR, Copyright NPR.

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