First, the U.S. Constitution. Impeachment is discussed in Article II, Section 4, in one sentence no less. For those who do not feel like clicking the link, here is the text of that section:
The President, Vice President and all civil officers of the United States, shall be removed from office on impeachment for, and conviction of, treason, bribery, or other high crimes and misdemeanors.
Well, simple enough, right? Not at all (as anyone who was conscious in 1998 will remember). The term impeachment is often wrongly understood as the actual removal of an official from his or her office. The impeachment, however, is merely the presentation of the charges against the accused (much like an indictment in a criminal case). The process of removing an official from office involves the impeachment, the presentation of evidence and then the subsequent vote on the charges by the responsible legislative body.
Historically speaking, the indictment power was discussed in the period that surrounded the writing and adoption of the U.S. Constitution between 1787 and 1789. In the most notable of these discussions, The Federalist Papers, Alexander Hamilton discusses the topic of impeachment.
In Federalist No. 65, Hamilton argues that it should be the Senate (with some members of the House of Representatives to serve as managers of the trial) that should serve as the court of impeachment. To allow the people to hear such trials would be, in Hamilton's estimation, to imflame popular passions. Hamilton's pathological distrust of the people aside, he only discusses the nature of the power briefly, at the beginning of the document.
There, Hamilton says that impeachment should be undertaken in cases of "misconduct of public men, or in other words, the abuse or violation of some public trust." It can be seen that this notion does not exactly match with the notion as defined in the final draft of the Constitution.
Taken together, the ambiguous terms from the Constitution and Federalist No. 65 present the central problem of calling for the impeachment of a federal official. Namely, what are "high crimes and misdemeanors" and what is an "abuse or violation of the public trust." These words will become quite the nub of the problem.
Perhaps it is germane to point out that the Constitution is the law of the land and The Federalist Papers are not. Still, they should provide further nuance to an understanding of this most confusing part of the U.S. Constitution.
The fact that there needs to be a set procedure for the removal of federal officials is obvious. What is not are the aforementioned terms and their meaning not only to us in the present, but also in divining the influences on people such as Alexander Hamilton to see if this issue can be made clearer.
Next time (at least the next time I feel like writing about impeachment), we shall look at the English precendent, use and possible influence on the Constitution and its provisions for impeachment. In England, briefly, the impeachment power was (up until the early modern period) taken to mean punitive action against anyone, official or not. It was in the seventeenth and eighteenth centuries that its sole use as punishment for those protected by the Crown (officials, that is) developed. This will be our focus.
More broadly, I intend to trace these precendents, look at three historical examples from the American past. Two from the nineteenth century (Chief Justice Samuel Chase in 1801 and President Andrew Johnson in 1868) and one from the twentieth century (Bill Clinton in 1998) will provide us with good consideration into the possibility of an impeachment of the current president.
After this is established, then we will look at possible charges against him, the likelihood of an impeachment/conviction and the broader implications of these (in the words of Former Chief Justice William Rehnquist) "grand inquests."
Until then, why not check out the Impeachment Information Center, an excellent source maintained by the Law School at the University of Pittsburgh.