DW: Does the firing of FBI director James Comey  (who led the FBI investigation into possible ties between Donald Trump, his associates and Russia), the explanations provided for this by the administration, or the reported Comey memo which allegedly states that Trump asked Comey to end the investigation into former National Security Adviser Michael Flynn provide any grounds for legal proceedings against President Trump?

Jack Balkin: The president of the United States, while he is in office, can be sued in a civil proceeding, but he can't be indicted criminally. So the only remedy available against a sitting president would be impeachment. After Trump fired Comey, many people thought that he had made out a case for obstruction of justice against himself because the federal statutes say it is a crime to purposefully interfere with an ongoing investigative proceeding. And it looks like this is exactly what he did.

At first his subordinates gave a justification for it that was completely unrelated to interfering with an ongoing proceeding, but then, in an interview with Lester Holt of NBC News, Trump basically said that they had all been lying, and that the reason he did it was to wind up the Russia investigation because he thought the Russia investigation was a big fake. And then everyone said "it looks like he is not a very good lawyer because he is just making the case against himself," but there was always some question whether or not it could be interpreted in an innocent way.

And then comes the revelation of this memo - that was written contemporaneously with a dinner - in which Trump is alleged to have asked Comey to stop the investigation of Michael Flynn on the grounds that Michael Flynn is a good fellow and he really does not deserve to have an investigation against him. At that point what Trump said in his justification for firing Comey looks increasingly like obstruction of justice. You have a high federal official, in this case the president, who is saying to the head of the FBI, which is the nation's chief investigative authority, ‘I know that you are investigating one of my subordinates who had to resign in disgrace, please stop the investigation.' And because the president has the power to fire the FBI director, that looks like he was trying to influence the FBI director to do what he wanted to do.

So you think there is a case for obstruction of justice?

If this were a criminal case you would have to prove bad intent, the attempt to deliberately obstruct and impede the investigation. But you can't bring a criminal investigation against a sitting US president under American law, and instead you have to proceed by impeachment. So the question then is whether the House of Representatives would then regard this as being a high crime or a misdemeanor. A high crime or misdemeanor, which is the constitutional provision, is a technical term and converts what one would ordinarily be a question of crime into a question of political crime.

Essentially, it's a judgment call for the House of Representatives, and they can be guided by the niceties of American criminal law. But they don't have to be entirely restricted by how courts have parsed particular criminal statutes. So disgrace of office, undermining the United States of America, disobeying the oath of office – all of these things could amount to a high crime or misdemeanor depending on what the House of Representatives thought; and then, of course, the Senate would actually have to pass on whether there is guilt or innocence. So the House is a kind of indictor and the Senate the judge.

In both the last two cases where there has been an impeachment crisis in America -, Richard Nixon and Bill Clinton -, on the list of impeachable offenses produced by the House of Representatives there has been a claim of obstruction of justice.

According to the US constitution Congress is tasked with oversight over the Executive Branch. Has Congress been doing its job so far?

No. One of the major problems with way in which the party system in the US has developed is that the parties in the US have increasingly become like parliamentary parties. That means they are relatively coherent ideologically and they basically work together. That means a Republican Party will not investigate a Republican president and the Democrats won't investigate a Democratic president. Now that we have the presidency and both houses of Congress controlled by Republicans you are not going to get any serious investigation – except that we have an amazing situation in which the president keeps making the case that he has committed a crime. At some point it will be politically impossible not to open an investigation.

But one of the puzzles of American politics today is that Americans seem to be getting two different sets of news and two different sets of facts - first, from the mainstream press, and second, from a relatively self-contained conservative media which basically reports what it wants to report. And so if you listen to mainstream media you see the president essentially making the case against himself for impeachment every day. If you listen to the self-contained conservative media it's much harder to discern that that's what's actually happening. And since the people who are in office - in the Republican Party - are elected by people who listen almost exclusively to the self-contained conservative media, they have much less incentive to actually do something, because they fear they will be punished by their constituents if they were to betray or abandon the president of the United States.

If you were the president's legal adviser what would you tell him?

If I were the president's legal adviser I would place a sock in his mouth, and then tape around the sock, and then I would put his fingers in mittens, and tape around the mittens so that he could never tweet again. I would keep him in a locked chamber and I would have an official representative make all of his public statements for him. I am barely exaggerating when I say this. The man is his own worst enemy.

Jack Balkin is professor of constitutional law and the first amendment at Yale University. He is also publisher of the legal blog Balkinization.

This interview was conducted by Michael Knigge.