Most Americans since then have continued to view the impeachment drive as partisan and unwarranted, even if they look askance at Clinton’s behavior. His defenders’ arguments—that even lying about his affair wasn’t a constitutional offense—were never seriously challenged. His acquittal in effect reaffirmed that impeachment shouldn’t be used for light and transient causes. Under both George W. Bush and Barack Obama, partisans at times issued demands for impeachment but party leaders always rejected them. Without evidence of wrongdoing so alarming that it would cause some of the president’s own supporters to break ranks, any such effort would lack the legitimacy it needs.

Needless to say, Congress shouldn’t shrink from investigating specific areas of Trump’s conduct, including those Leonhardt enumerated last week. Now that they’re run by Democrats, House committees can probe the legality of Trump’s mingling of government and private business. They can study the constitutionality of his firing FBI Director James Comey—and of other possible obstructions of the collusion inquiry. And they can probe whether he has systematically placed Russia’s interest before America’s. Public hearings could be as revealing as those the Senate Watergate Committee held in 1973.

But Democrats would also be wise to trust House Judiciary Chairman Jerrold Nadler, who wants to defer talk of impeachment until such investigations progress. Without support from “a good fraction of the opposition” party, Nadler said, an impeachment drive would “tear the country apart.”