MICHEL MARTIN, HOST:

Now we'd like to turn to a relatively arcane issue that often surfaces in the closing days of an administration - executive clemency. President Obama is days away from leaving the White House. And historically, that's when some of the most controversial requests for clemency are granted. On his last day in office, President Bill Clinton pardoned fugitive Marc Rich, who'd been charged with tax evasion. During his last month in office, President George H.W. Bush pardoned his defense secretary, Caspar Weinberger, for his role in the Iran-Contra scandal.

President Obama has already established important precedence in executive clemency, having commuted the sentences of more than a thousand people so far. In nearly all those cases, he commuted sentences of nonviolent drug offenders who would be out of prison under modern sentencing guidelines. But in the next few days, people will be watching to see if President Obama does anything on particularly controversial cases that may be under consideration, like that of Edward Snowden, who publicized the U.S.'s secret data collection program.

To find out more, we called someone who studies clemency closely. Professor Ronald S. Sullivan Jr. is the director of the Criminal Justice Institute at Harvard University. I started out by asking him whether these last-minute requests for clemency make a difference.

RONALD S SULLIVAN JR: Well, yes, I think it does. We will never know how much of a difference it makes. The power of pardon, the power of clemency is one of the few powers that rests unrestrained in the office of the president. I'm in the middle of another one. I represent the family of Jack Johnson, the country's first African-American heavyweight championship. And I am sending in a last-minute posthumous pardon request to the president. And I hope he is moved by some public pressure because there are a lot of people who really think that this pardon ought to go through.

MARTIN: On what grounds? Tell me about that. Tell me a little bit more about Jack Johnson. Tell me a little bit more about that story.

SULLIVAN: Oh, well, Jack Johnson was convicted under something called the Mann Act. He was an African-American man who had married a white woman. Sexual relations between African-Americans and whites in that era was legally prohibited, so the prosecution and the conviction was clearly based on race bias. So we certainly hope that this will be another example of a posthumous pardon.

MARTIN: And what about the controversial cases that have started getting public attention - Edward Snowden, Leonard Peltier - thoughts about that? I am asking you predict, but - I apologize, but I am interested in your prediction.

SULLIVAN: (Laughter) So those are interesting cases. So what historically has happened - it is a way for the executive branch to correct manifest injustices that occur in the judicial system. So with respect to cases like Snowden, is there a reasonable and articulable injustice that Edward Snowden suffered or is suffering in the justice system? It really depends on the way in which the president views Snowden's actions.

Does he view him more as a patriot or more as a person who knowingly violated the law? If it's the latter, then that is not consistent with the historic justifications for the pardon. If it's the former, then the president very well may do it. So my prediction with Snowden is no.

MARTIN: Very interesting. Before we let you go, I understand that this is a story with a final chapter yet to be written, which will be written in the next couple of days. But from what you know now, what do you think President Obama's legacy will be on executive pardons, executive clemency?

SULLIVAN: I think his legacy on pardons generally will be that he was very cautious with respect to persons who are convicted or who were convicted of drug crimes. I think he will go down in history as one of the most aggressive users of the pardon privilege. He's done more, as you said, than the past 11 presidents combined, and I really hope in these last few days that he will.

MARTIN: That was Harvard University law professor Ron Sullivan. He was kind enough to join us from his home office in Cambridge, Mass. Professor Sullivan, thank you so much for speaking with us.

SULLIVAN: Thanks so much and take care. Transcript provided by NPR, Copyright NPR.