The text and Hamilton’s commentary are sufficiently clear: those in office are subject to impeachment and trial; those out of office are not.
I have long believed that the House Republicans should be using their impeachment power against the IRS. I thought that they should have seriously considered impeaching Lois Lerner (although I suppose there is question whether she was a constitutional officer). I certainly believe that they should consider whether to impeach IRS Commissioner John Koskinen and other relevant IRS officials. (Note: the House impeaches or accuses; the Senate tries the official and can convict with a two thirds majority.)
It is true that an impeachment of the IRS Commissioner will not directly affect the President or the White House. But it is important to use the tools that the Congress has to police wrongdoing and impeachment is one of them.
Impeachment will punish the wrongdoing of officials in an entirely constitutional way. The accused person will have the spotlight on them and their acts will be exposed to the public. If they are removed from office, they will be in disgrace. Moreover, the media will find it much harder to ignore the issue, both because of the unusualness of an impeachment and because of the drama that it establishes. Impeachment will command the attention of the country in a way that simple oversight hearings do not.
Nor will the impeachment leave the White House unaffected. Once it becomes clear that officials may be impeached, their will be greater reluctance on the part of officials to engage in wrongdoing. Moreover, the impeachment may reveal information about wrongdoing by the White House.
An impeachment will provide the House with more power than simple oversight hearings. There is a strong argument that executive privilege will either not be available or will be much less available against an impeachment inquiry.
It is true that while the House can impeach an official with a majority vote, a conviction and removal from office requires a two thirds vote of the Senate. Thus, depending on the evidence against the official and the degree of politics at work in the Senate, it is possible that an official who should be removed would not be convicted in the Senate. But that is not a serious problem in my view.
First, even if the official is acquitted, they will hardly get off scot-free. Significant evidence will have been presented against them in the public arena, and one house will be have charged them. The other house might have acquitted them, but it is likely a majority of the Senate would have voted for conviction and the remaining Senators would have voted for acquittal as a defense of their party’s administration. This is hardly an exoneration.
Second, if the evidence is strong, these Democratic Senators may not feel free to vote for acquittal. And that will send a strong message – that two thirds of the Senate, with members from both parties, found serious wrongdoing.