The Democratic chairman of the Senate Judiciary Committee says he plans to hold a hearing in January to consider changing federal drug laws to allow people to possess up to one ounce of marijuana. On Thursday, Sen. Patrick Leahy (D-Vt.) released a letter that he sent earlier this month to Gil Kerlikowske, the director of the Office of National Drug Control Policy (ONDCP), asking the nation’s drug czar how the administration intends to proceed now that two states have legalized marijuana use. …