House Democrats have finally vouchsafed to deliver their impeachment articles to the Senate, a month after they claimed their rushed votes were essential to save the republic. The Senate can now do better by the Constitution by holding a trial that judges President Trump without validating the partisan House process and its weak case.

Nancy Pelosi’s delay in appointing House managers further exposes how Democrats have defined impeachment down. The House hearings blocked GOP witnesses and limited cross-examination. Despite...