Remember the “subpoena cannon”? This was the metaphor for how Democrats planned to use their new majority in the House—and chairmanships of key committees—to dig into every aspect of Donald Trump’s life. We have now arrived at stage two: an omnibus contempt bill.

The Judiciary Committee kicked it off last Wednesday, when it voted to hold Attorney General William Barr in contempt for refusing to turn over a completely unredacted version of special counsel Robert Mueller’s report. Normally the contempt resolution would move...