To answer these questions, we have to ask another question. To some, this is a distinction without a difference, but I believe the framers of our Constitution contemplated a distinction when they wrote of treason, bribery, and other high crimes and misdemeanors. But if the sin were committed by Bill Clinton the man, sins nonetheless, the decision becomes more difficult. Not all crimes are impeachable. One must examine the conduct in question to determine whether it is impeachable.
Most offenses undermine one thing or another.
That is why they are proscribed by the criminal law. Most people would agree that running a red light does not fall within that narrow category of offenses that are impeachable, but if everyone did it, countless people would die on unsafe streets. So the question isn't whether lying under oath or perjury undermine the system of justice in a general sense. The question is whether the specific conduct represents a grave offense against the state and is a threat to our system of government. Assuming that the evidence before us, most of it hearsay untested by cross-examination, did establish perjury and obstruction of justice, I would have to conclude that the matters the president allegedly lied about, the matters he allegedly obstructed justice about, are not, except in the most attenuated, abstract sense, a threat to our system of government.