Washington (CNN) Late Thursday, The Washington Post reported that President Donald Trump is seeking to understand his pardon power, a development that seems directly linked to the ongoing special counsel investigation into Russian meddling in the 2016 election and possible collusion between the Trump campaign and the foreign power.

The Post raises the possibility of Trump pardoning top advisers, family members and even himself. Friday morning, John Dowd from Trump's legal team called the Post story about Trump considering pardons "nonsense."

But it is still a good question: Can he do that? To answer that question, I reached out to Brian C. Kalt . Kalt is a professor of law at Michigan State University and the author of a 2012 book entitled " Constitutional Cliffhangers: A Legal Guide for Presidents and Their Enemies ." Our conversation, conducted via email and lightly edited for flow, is below.

Cillizza: Let's start with the Constitution. What does it say, specifically, about presidential pardoning power?

The only other limits are things that are implicit in the definition of a "pardon." So, for instance, a pardon can only reach things you already did. It can't suspend the law in advance, because that wouldn't be a "pardon."

Cillizza: Can a president actually even be prosecuted in office?

Kalt: It's not clear. I (in Chapter 1 of my book, "Constitutional Cliffhangers: A Legal Guide for Presidents and Their Enemies") and many others have argued that presidents cannot be prosecuted while in office, but the argument is complicated and there are points on both sides.

The Constitution does not explicitly provide for presidential immunity, and that's good enough for some people to say a prosecution would be fine. But the Constitution also makes the president the head of the executive branch that would be doing any federal prosecuting, so a president couldn't really be prosecuted by the federal government unless he effectively consented.

It is very awkward to have even an independent counsel go after the president, because the president's ultimate control over the executive branch means that the president can derail the investigation as long as he is willing to pay the political price. State prosecutions are awkward too, because having one county district attorney haul the president of the whole country into one is structurally awkward.

If you like the idea of one county DA whose ideology you share having that power and using it against a president you dislike, ask yourself if you would like it if the parties were reversed. Imagine a county DA with politics opposite yours, pursuing a president you like.

Impeachment provides another structural piece of the puzzle. There is broader consensus that presidents can be prosecuted once they have left office, and impeachment can hasten that day.

Cillizza: No president has ever pardoned himself. But what about the pardon of a top adviser? And what was the blowback if any?

Kalt: One example was : One example was President Bush (43)'s commutation of Scooter Libby's sentence , but that did not make a very big splash. Another example is President Bush (41), when he pardoned Caspar Weinberger and other Reagan administration officials in December 1992 regarding the Iran-Contra affair. They were not his aides, but he had worked alongside them in the previous administration and Bush was swept up in the scandal to some extent as well. But Bush had already lost the election, so there was nothing much for the blowback to blow back on.

Cillizza: Presidential pardons have become a late-in-the-term move due to the controversy they cause. Has that always been the case, historically speaking?

Kalt: Historically, there does seem to be a slight increase in the use of the pardon power toward the end of terms, but not a lot of overly controversial ones.

More recently, though, we saw very controversial lame duck pardons by Bush(41) (as mentioned above) and by President Clinton, who pardoned Marc Rich, Susan McDougal, and his brother, Roger Clinton, among many others, on his way out of office. Given what happened to President Ford -- who pardoned President Nixon in 1974 and then lost the election in 1976 partly as a result -- you can see why they might have wanted to wait until after the election (even if a president isn't running for re-election, like Clinton in 2001, he might want to avoid harming his party's prospects).

But one of the reasons that the framers of the Constitution gave the pardon power to the president was that he is politically accountable. That makes it troubling when presidents wait until the end [of their term], when they are at their least accountable, to issue controversial pardons.

Cillizza: Finish this sentence: "The chances of a president being able to pardon himself are roughly ______%." Now, explain.

Kalt: Ha! I have been studying self-pardons and writing about them for over 20 years now (including in Chapter 2 of my book), and I have thoroughly convinced myself that any court faced with the issue should rule against self-pardons' validity. But "should" and "would" are two different things, and it is so hard to predict just what the Supreme Court would do that I can't say with any precision. I'll just say that I think it's less than 50%, but not close to 0%.

On the president's side is the fact that the Constitution does not expressly prohibit self-pardons.

The argument is a bit more complicated on the prosecution's side -- that's how it would get to court; the president would have to pardon himself and the prosecutor would have to prosecute him anyway, presumably after the president had left office.

First, as I said in my answer to [your first question], there are limits in the pardon power implicit in the notion of what a "pardon" is. So the prosecutor would say that a pardon is inherently bilateral -- something you can only give to someone else. "Pardon" comes from the same Latin root as "donate," and it doesn't make sense to speak of donating things to yourself.

Second, there is a venerable principle in the law that no one can be the judge in his own case. We would not permit a judge to preside over his own trial, for instance. So we would say here that if a president wants a pardon he has to get it from someone else, i.e., a successor.

Third, there are some historical arguments that support the idea that the framers of the Constitution assumed presidents could not pardon themselves.

One could also interpret your question more practically: What are the chances that a president would feel able to get away with a self-pardon. Given how bad it would look, how it provides grounds for impeachment, and how it could even be a crime of its own (similar to how a pardon given in exchange for a bribe could be prosecuted as a bribe, a pardon given to obstruct justice could be prosecuted as obstruction of justice), and given how it would not affect any state prosecutions, presidents have lots of good reasons not to try to pardon themselves.