Their falsehoods were immoral, divisive, and quite possibly unlawful. On Friday afternoon, two of the leading contenders in the Democratic presidential primary lied. There’s no other fair way to put it. They flat-out spread fiction, libeled an innocent man, and stoked American divisions — all for political gain. Five years ago, a Ferguson, Mo., police officer named Darren Wilson shot a young black man named Michael Brown to death after an altercation in the street. False rumors about Brown’s death — namely that he was shot in cold blood while trying to surrender with his hands in the air —...