WORCESTER, Mass. — With Democratic control of Congress after 2018 increasingly plausible, those who most intensely seek the impeachment of President Trump are organizing, agitating — and conducting a veritable clinic in how not to exercise one of the Constitution’s most solemn powers.

Investigations are still underway, but 58 House Democrats have already voted to consider impeaching Mr. Trump. Tom Steyer, a Democratic megadonor, is running a multipronged campaign calling for Mr. Trump’s impeachment on grounds ranging from his North Korea policy to allegations of obstruction of justice.

It is true that impeachment is a political rather than a criminal device, but not like this. It requires the kind of political judgment concerned with the public good, not with gaining electoral advantage. The prudent path forward lies somewhere between “fiat justitia, ruat caelum” and “Vox populi, vox Dei” — “let justice be done though the heavens fall” on one hand and “the voice of the people is the voice of God” on the other.

Mr. Trump may well have committed impeachable offenses. Many presidents have. The nature of the office, whose governing rules cannot speak to every exigency, inevitably requires risking oneself in the manner Thomas Jefferson described: “An officer is bound to obey orders; yet he would be a bad one who should do it in cases for which they were not intended, and which involved the most important consequences.”