The Jan. 6 hearings are over. Time to vote.

The House committee investigating the Jan. 6 Capitol attack has held what is expected to be its final public hearing, driving home a conclusion that once would have been unthinkable, but now is inescapable: The president of the United States was directly responsible for an assault on the nation’s government.

Donald Trump dodged accountability for the Jan. 6, 2021, attack on the U.S. Capitol when Senate Republicans acquitted him the following month in his second impeachment trial. Prosecuting the former president raises complex questions of law — and about whether doing so would ultimately set...