In this manner, the president could undermine impeachment by inducing witnesses to perjure themselves. This practice would go far to achieve the result the framers most feared: unchecked power in the hands of the executive. Of course, courts would presumably still enforce separation of powers, and the president would still be subject to an electoral check. Nevertheless, a president effectively freed from the check of impeachment would represent a dangerous alteration in the balance of governmental power.

Presidential suborning of perjury is itself most likely an impeachable offense. But the impeachment remedy for such presidential misdeeds may well prove to be insufficient for checking a president’s guerrilla warfare on the impeachment process. For example, what if Congress is unable to unearth persuasive evidence of such behavior, even though it actually took place, or what if the president preemptively pardons perjuring witnesses as a means of stopping any investigation into their behavior? What if witnesses friendly to the president choose to perjure themselves, assuming that the president will pardon them? In other words, even the mere possibility of presidential pardon in such situations presents a serious threat to the effective use of the impeachment power. It is reasonable, then, to find presidential pardon of witnesses in an impeachment proceeding automatically invalid. Otherwise, exercise of the pardon power seriously threatens the effective use of the impeachment power as a constitutional check.

The obvious means of avoiding such a troubling situation is to establish a prophylactic barrier to presidential pardon of any impeachment witness convicted of perjury or contempt. Can the Constitution be construed as establishing such a barrier? The answer is yes, if we choose to construe the pardon power’s impeachment exception to prohibit not only presidential pardons of impeachment convictions but also pardons of those convicted of criminal undermining of the impeachment process.

Is this expansion of the impeachment qualification on the pardon power consistent with the framers’ understanding? Technically, perhaps not, though slavish adherence to the framers’ understanding has by no means always limited modern constitutional interpretation. Indeed, much of modern constitutional law has evolved without concern for what the framers did or did not intend. It is also important to note that this reading of the pardon power’s impeachment exception is linguistically consistent with the text: “except in cases of impeachment” arguably refers to any crime related to the impeachment, as much as it does to the narrow conviction. This relatively expansive reading of the impeachment exception better fulfills the framers’ goals in adopting the impeachment exception to the pardon power in the first place — to prevent the president from undermining the impeachment power’s check of abuse of political or judicial authority.