Choooo-choooo. Not since Casey Jones has there been a train wreck as spectacular as the one in which the district attorney of Fulton County ran off the rails in her effort to prosecute President Trump for election interference. With each passing challenge to the way the D.A., Fani Willis, was conducting the case, she vowed to press on — saying, at one point, “I do think there are efforts to slow down this train, but the train is coming.”

Today a panel of a state appeals court in Georgia hit the brakes. It removed from the case not only Ms. Willis but her entire office. The logic for that, our A.R. Hoffman explains, follows from the fact that the authority to prosecute is vested in the elected district attorney, not in her legal staff. It’s not too soon to suggest that this represents a huge step forward for President-elect Trump and his co-defendants. It is too soon, though, to suggest the case is over.