A US NLRB judge ruled that Amazon violated federal law by not recognizing the Teamsters union at a SF warehouse and must collectively bargain with the workers (Josh Eidelson/Bloomberg)

Josh Eidelson / Bloomberg: A US NLRB judge ruled that Amazon violated federal law by not recognizing the Teamsters union at a SF warehouse and must collectively bargain with the workers — A US labor board judge ruled that Amazon.com Inc. must collectively bargain with California warehouse workers …