I still like to start with the words of the Constitution which, being a declaration of the ordinary People, the words have ordinary and usual meaning, not twisted judge/shyster language.
Art I § 3 clause 7 in plain language (the 2 ¶ below) allows indictment, trial, judgment & punishment in addition to impeachment or, it appears, even without impeachment. In other words, it is possible to impeach first, then indict and criminally punish–because the punishment for impeachment is limited to removal and disqualification for “any office of honor, trust or profit under the United States.”
However, the criminal process is not limited by the express language to after impeachment. Rather I suggest it was to make clear impeachment first does not implicate double jeopardy rights of the accused. Nor is it rational that the Framers thought a person of such dishonor as to be a criminal ought to be the chief law enforcement officer of the US hence–impeach him and remove from office. But, because no onei s above the law, that is not the end, following impeachment criminal prosecution can take place. Nothing in the express language prohibits”Indictment, Trial, Judgment and Punishment, according to Law” prior to or independent of impeachment.
The control of the House and the Senate by the President’s “faction” (now known as party) could put him above impeachment, even after the new Congress is sworn in next month. His crimes under state or federal law, however, are not political matters and the full force of the law against criminals ought to attach independent of impeachment, or the very person charged with a duty to “faithfully execute the law” holds others criminally responsible while being criminal himself. Such an outcome is not consistent with an “office of honor,” as the office of the President ought to be.
A conclusion the President is above the law would need an express power granted the President and none is stated in Art II, nor elsewhere in the Constitution. A criminal president is a criminal. All criminals are subject to the law equally with all other citizens. None are exempted anywhere in the Constitution, except those receiving pardons, and those are only as to federal crimes–and pardons are not permitted if they are a part of a quid pro quo that trades favors for freedom contrary to the rule of law–for example, if Manafort were to lie to protect Trump, Trump could not pardon Manafort without committing yet another crime, Obstruction of Justice. It is somewhat sad to be compelled to such analysis at all, but that is the price of “an office of honor.” It cannot be dishonorably discharged and remain “honorable”—that is simply illogical.
The illogic of allowing a criminal immunity because he won a job whose duty was to faithfully execute the law makes the law an ass. The president may be an ass, he may be a criminal, but the law ought not to be, and allowing a criminal to persist in the office of the presidency, even with the complicity of the House and Senate, is incompatible with a government of law and the “honorable” office of the presidency.