When it comes to the subject of marijuana, Barack Obama appears to talk out of both sides of his mouth. As a candidate, Obama intimated that he would respect state laws regarding medicinal marijuana and would not prosecute medicinal marijuana sales and use in states where it is legal. “It’s not a good use of our resources,” he said at the time. When Obama took office, the Justice Department released a memo that seemed to confirm that position. But in the years since Obama’s inauguration, his administration has shifted course. Now, Attorney General Eric Holder is vigorously prosecuting medicinal marijuana...