President Obama’s latest claims about marijuana are contradicted by research and official positions of the Office of National Drug Control Policy, which is part of the White House. And Mr. Obama’s words have anti-drug leaders worried about negative repercussions among youth. Mr. Obama claimed to The New Yorker magazine that marijuana is no worse than cigarettes or alcohol and he promoted state efforts by Colorado and Washington to legalize marijuana, which remains illegal under federal law. The National Drug Control Policy’s official stance, posted on the whitehouse.gov website, says the opposite of Mr. Obama on all counts. For example, as...