SEATTLE – In two weeks, adults in this state will no longer be arrested or incarcerated for something that nearly 30 million Americans did last year. For the first time since prohibition began 75 years ago, recreational marijuana use will be legal; the misery-inducing crusade to lock up thousands of ordinary people has at last been seen, by a majority of voters in this state and in Colorado, for what it is: a monumental failure. That is, unless the Obama administration steps in with an injunction, as it has threatened to in the past, against common sense. For what stands...