Introduction
One of the most valued ideas in the United States is that no one is above the law, not even Congress or the President. This equality isn’t always played out in real life. However, it is reassuring that the US Constitution has a process for requiring even the highest officeholders to answer for abuse of power and criminal actions: impeachment. Impeachment is the first step in removing a President or other Federal official from office.
Impeachment in the United States is an action by the House of Representatives, charging a Federal official with “Treason, Bribery, or other high Crimes and Misdemeanors” (Article II, Section 4, of the US Constitution). If the House decides in favor of impeachment, the Senate follows with a trial where, if the person is found guilty, the official is thrown out of power. Essentially, they’re fired. This is very rare and most often is applied to federal judges, though holders of higher offices (including the Presidency) can also be impeached.
In the modern US, impeachment is a drastic step that can take over the Congressional agenda (and the political discourse) for many months. Unless there is clear proof of guilt, Congress typically seeks out any other solution. Even then, the official in question can resign before articles of impeachment are brought against them. There are also impeachments at the state level, though the laws differ somewhat across the states.
History of Impeachment
American impeachment law is a direct descendant of British impeachment practices, which date from the 1300s. Impeachment was created so that the English parliament could ensure that the monarch’s officials remained within the law. In England an impeached person wouldn’t only be tossed out of office or given a fine: they could be named a criminal or arrested! In the 1600s, English officials had to be careful not to be impeached for being unpopular (with their coworkers or the King himself). Remnants of these early systems have survived. This includes the idea of impeachment being similar to a charge or an indictment, which is then followed by a trial; the US has adopted this approach (without the criminal aspect).
Though the American Revolution threw the British out of the 13 original colonies, many English laws made their way into the US political system. The idea of impeachment was one of these; multiple colonies had impeachment in their law codes before the Revolution. Impeachment was written into the US Constitution (in Article II, section 4), making it a Federal (national) procedure. As defined in the Constitution, impeachment does not lead to a criminal trial. Instead, it’s a procedure that just determines whether the person should be removed from office or should be allowed to continue to hold their job.
How Impeachment Works
The House of Representatives enacts the initial impeachment accusation. One or more representatives put forward the impeachment charge, and it is usually referred to a committee to see if it agrees that there is merit to the allegation. 
The entire House then meets to debate and vote. If the impeachment vote passes in the House, the process moves to the Senate, which holds the impeachment trial. Only if the Senate votes to convict will the individual be removed from office. The House only needs a simple majority vote to impeach, but a two-thirds vote is required in the Senate to convict and remove from office.
Members of the Senate (and presumably the House of Representatives) are an interesting exception to this. A strange precedent happened in 1797, when Senator William Blount was accused of treason. He became the first Federal official that the House impeached. But before any impeachment trial could be held, the Senate went ahead and removed him from office, just by taking an expulsion vote (separately from the impeachment process). So, while the Constitution apparently allows a Senator to be impeached, but the one time this happened, the Senate refused to hold an impeachment trial. No member of Congress other than Sen. Blount has been impeached in US history.
Impeachment is not an actual criminal charge in the United States. However, after the impeachment, the former official could possibly be charged in a criminal court, depending on the nature of the offense.
What’s Impeachable?
There isn’t a strict guidebook as to why someone can be impeached. Impeachment can occur if a Federal official broke a law: specifically, according to the Constitution, if they are guilty of “Treason, Bribery, or other high Crimes and Misdemeanors” (Article II, Section 4). This is not only incredibly vague but also quite hard to prove, particularly as the government might shy away from condemning officials in higher offices. As of 2018, the House of Representatives has impeached 19 officials, and the Senate has removed only eight of them from their positions.
Most of the impeached have been Federal judges who were charged with negligence or corruption. Some who the House impeached but who were not convicted by the Senate were: Senator William Blount (in 1797), President Andrew Johnson (in 1868), Secretary of War William Belknap (in 1876), President William (Bill) Clinton (in 1998), and President Donald Trump (twice — the first time in 2019-2020, and then again in 2021). The House began impeachment procedures against President Richard Nixon in 1974, but he resigned before they could conclude.
The Presidential Impeachments
Only five times in American history has a President of the United States been impeached or come close to impeachment. Four Presidents reached this point: Andrew Johnson, Richard Nixon, William (Bill) Clinton, and Donald Trump (twice). Nixon knew he would probably be impeached by the House, and he resigned before an impeachment vote was taken. Johnson, Clinton, and Trump were acquitted (found “not guilty”) by the Senate, although Johnson escaped conviction by just a single vote. Though Johnson, Clinton, and Trump were impeached by the House of Representatives, all three were ultimately acquitted by the Senate and kept their jobs. (Trump’s second impeachment was after he was no longer the President, but he was acquitted that time also.)
President Johnson’s impeachment trial in 1868 concerned whether he had exceeded his Presidential powers by trying to remove his Secretary of War. For context: after the Civil War, Johnson and the Congress disagreed over who was in charge of Reconstruction in the South. In 1867, Congress passed the Tenure of Office Act, which made it illegal for the President to dismiss his Cabinet members without the approval of Congress. When Johnson fell afoul of the Act, he was impeached by the House, but was then found not guilty by the Senate.
In 1974 President Nixon was complicit in the Watergate scandal (which was about a break-in at the Democratic National Committee’s headquarters as well as how the Nixon administration covered it up afterwards). If Nixon hadn’t resigned, he would almost certainly have been impeached and removed from office.
In 1998, President Clinton was in the midst of a scandal regarding marital affairs, and what got him into official trouble was that he lied to a grand jury in connection with a lawsuit filed by Paula Jones, and urged others to lie, and was thus accused of perjury, obstruction of justice, and abuse of power. As in the case of Andrew Johnson, Clinton was impeached by the House, but the Senate acquitted him, so he was not removed from office.
In late 2019, the House of Representatives voted for two articles of impeachment against President Trump. The first alleged that Trump had committed an abuse of power, trying to influence Ukraine to investigate corruption claims against Sen. Joe Biden and his son Hunter. The second article of impeachment alleged obstruction of Congress because of Trump’s lack of cooperation with the House’s impeachment inquiry. The Senate trial in 2020 acquitted Trump on both charges, so the President stayed in office. Both the impeachment votes in the House and the acquittal votes in the Senate were largely along partisan lines.
President Trump’s term ended on January 20, 2021. But in early February 2021, the House voted to impeach him a second time, even though he was no longer in office. He was charged with encouraging supporters who violently stormed the Capitol on January 6 as they attempted to disrupt the certification of Joe Biden’s election as the next President. The single article of impeachment was entitled “Incitement of Insurrection.” There was some dispute as to whether there could be an impeachment trial of a former President (the case seemed like it might be moot since removal from office was no longer a possibility), but there was some precedent for so-called late impeachment; a majority of the Senate decided to proceed because conviction could be accompanied by a prohibition against him running for public office in the future. So the Senate held a trial, but once again, the verdict was an acquittal. Those Senators who voted against conviction did so in part because President Trump’s words did not specifically call for violence and in part because they disagreed with the legal assessment that a former President could be impeached.
The 25th Amendment
Apart from the impeachment process, the only part of the US Constitution that could be used to remove a President is the 25th Amendment. This Amendment, among other things, allows for a President to be forced aside if he or she is physically incapable of performing the job.
Conclusion
Impeachment is an extreme action that is not taken lightly. But this rare procedure is incredibly important. The very fact that impeachment exists establishes that no one is above the law in the United States. This admittedly idealistic statement is nevertheless crucial: it provides a defense from official wrongdoing or abuse of power, while cementing the principle of equality before the law.