Poor Jerry Nadler.

The congressman from New York has been itching to get Donald Trump almost from the day he was elected president. Alas, just as Mr. Nadler finds himself in a position to do it—as House Judiciary Committee chairman he has jurisdiction over impeachment proceedings—special counsel Robert Mueller dropped a report that found zero evidence of collusion with Russia. With no crime to cover up, what would the president have been obstructing?

But...