TUCSON — “My record is 30 minutes,” Magistrate Judge Bernardo P. Velasco of Federal District Court here said one afternoon, describing the speed with which he had sealed the fates of a batch of 70 migrants caught sneaking into the country. Each of the accused had 25 seconds, give or take, to hear the charges against him, enter a plea and receive a sentence. This is a part of the battle against illegal immigration that many Americans have never heard of. Known as Operation Streamline, it is the core of a federal program that operates in three border states, using...