The power to impeach officers of the United State government is one of the gravest powers entrusted to Congress in the U.S. Constitution. The power is far-ranging and flexible, laying at the feet of Congress the ultimate responsibility to insure that the officers of the federal government are acting in the national interest and not abusing their authority. Congress has not had many occasions to use the power over the course of the nation's history, and the most frequent targets have been low-level judges who had engaged in undoubtedly bad behavior. Impeachments of more high-profile targets like presidents raise more difficult political and constitutional issues about how the power should be used and what the role of the impeachment power might be within the American constitutional system.
We might distinguish among three uses of the impeachment power, which I will call the political, the personal, and the constitutional. I believe that we should largely reject the first, and should be very cautious of the second. We do not always appreciate the significance of the third.