And the key word there is “high crime.” A regular crime is against someone else or against the nature of state law, but not against the authority of state law. A high crime is one that's designed to damage the people, the sovereign authority — which is to say that a high crime need not be a crime in a technical sense. It need not be illegal in order to be a high crime. A high crime doesn't have to be on the books. By the same token, if a President were to commit a regular crime, that would not be an impeachable offense according to the Founders either. The example I like to give is jaywalking. A President could jaywalk, which is a crime, and could be guilty of it, and could be found guilty of it. But nobody in their right mind would think that jaywalking is a reason to make somebody leave office. It has to be something that is broader, that's an assault against the sovereign nature of the state.
OR: What about the history of impeachments themselves?
Engel: There are really three major cases: Andrew Johnson, Richard Nixon, and Bill Clinton. I actually think a fourth one is almost as illustrative: John Tyler, who's a really fascinating President. He's the first President to come into power because of the death of a President, the first vice President to assume because of death. Tyler took over from William Henry Harrison, who famously died after three weeks in office. Tyler's case is really fascinating. He was not a natural political ally of Harrison. Harrison's Cabinet had been selected by Harrison, obviously, and included all of the major players in his party. This Cabinet essentially proposed to Tyler that his job as Vice President, having become President, was to be the acting President. That he was supposed to execute the policies of the President, i.e., the policies the people voted for, and that that was his Constitutional duty.
Tyler told them to stick that argument where the sun doesn't shine and said, "I am the President, and I have a moral and legal and constitutional authority to act in the best interests of the country as I see it, not as I imagine a dead President might have seen it." And you can imagine this made him very unpopular within his Cabinet and his own party, and there was a lot of discussion of impeachment at that time. It didn't get beyond the discussion stage but it raised a real and important philosophical point in American circles: that the man or woman who holds the office is the President, period. There is no “acting” involved. There is no sense of office place-holding involved. President Tyler, in fact, refused to open any mail that was addressed to the Acting President.
This raises a broader point. The few times where we've had a Vice President assume the presidency, people make a big deal of the fact that he has to take the oath of office. He doesn't actually have to take the oath of office. The vice President is the President the moment that the President is no longer the President (if that makes sense). The moment Kennedy is shot, Lyndon Johnson is the President. Now, for legitimacy reasons and for a good photo op, they have always traditionally taken the oath of office. But in a legal sense it is unnecessary, and Tyler's reign demonstrates that point.
The first time impeachment becomes legislatively critical is with Andrew Johnson, who, of course, is the President who assumed power after Abraham Lincoln was killed. Johnson, we should remember, was never a member of Lincoln's party. Johnson was a Democrat who Lincoln had reached out to in 1864 to try to create a bipartisan ticket. He was the only Southern Democrat Senator to remain in the Senate. He didn't leave when his home state seceded.
He was a Southerner with Southern leanings: he was in favor of the Union, but he certainly was functionally pro-slavery and functionally anti civil-rights — and he becomes the person in charge during a time when the Republican Party has a complete hold on Congress. He proves to be really frustrating to Congressional leaders, who want to be radical in their reconstruction of the South. They want to push forward all kinds of civil rights legislation and electoral legislation that would have really upended the social structure of the South. Johnson refused to sign onto that.
Johnson may be the most racist person to ever hold the office. It's hard to quantify that, but he would have to be in the discussion. He was also a jerk to everyone. He had no political friends or constituency willing to lay down for him on either side of the aisle. So by the end of his term, enough enthusiasm had risen among Republicans to remove him that they get into a brouhaha over whether or not Johnson has the legal authority to fire a Cabinet member who has been approved by Congress. Congress passes legislation that says the President does not have the authority. Johnson claims he does have the authority. Johnson fires the Secretary of War, Edwin Stanton, and violates Congressional will in a manner that appears to be unconstitutional, which is ultimately why he is brought up on charges and impeached in the House. It should be noted that the Supreme Court subsequently, in the 1880’s, ruled that legislation itself unconstitutional, so Johnson was right in that narrow sense. He was impeached but not convicted for two reasons. First, because there were enough Republican Senators who thought it was wrong to remove a President who, again, was doing his job as he saw fit. Just because he was wrong doesn't mean that he should be impeached. The second thing is Johnson and his allies bribed the hell out of the Senate, and several of the Senators voted to acquit him wound up becoming very rich or well-positioned immediately afterwards. If you were on the fence and you let Johnson's people know that you could be bought, they were more than willing to buy you.
A leading presidential historian makes the case the the Founders would be baffled why we have not already impeached for Donald Trump.