Think the fog of partisan Trump investigations will lift once the President leaves office, either in 2021 or 2025? Not if Elizabeth Warren has anything to say about it. With the Iowa caucuses approaching and her campaign fortunes flagging, Senator Warren now says that as President she’d launch an open-ended criminal investigation into her predecessor and anyone who worked for him.

Ms. Warren’s latest “anti-corruption” plan says she would create “a Justice Department Task Force to investigate corruption during the Trump administration and to hold government officials accountable for illegal activity.” She would order Justice to look for violations of “federal bribery laws, insider trading laws, and other anti-corruption and public integrity laws” as well as immigration-enforcement offenses.

“This will be no ordinary transition between administrations,” the document says ominously. Team Warren won’t be satisfied with taking control of the executive branch in an election. They also want scalps of choice ex-officials. The plan links to news articles about Commerce Secretary Wilbur Ross, White House Adviser KellyanneConway and Secretary of Housing and Urban Development Ben Carson.

If there is evidence of a crime by a former Administration official, it should be investigated through the normal channels. Ms. Warren is proposing something different: A law-enforcement task force dedicated to searching for wrongdoing only by political opponents. This would be familiar in Latin American dictatorships where the party that loses an election may be jailed as retribution.

Pundits said Mr. Trump’s 2016 campaign threat to investigate Hillary Clinton for her email mismanagement was a chilling breach of democratic norms. We opposed such an investigation but at least the alleged misconduct was limited to specific conduct by one official, whereas Ms. Warren wants investigations of all Republican officials for any political offenses.