Jared Polis on Thursday signed into law what may be the toughest gun control regulations in state history. Under the new law, it is illegal to buy, sell and make most semi-automatic firearms without background checks and training.

Colorado’s Democratic Gov. Jared Polis has signed a bill requiring people to pass a background check and complete a state-sanctioned safety course to buy most semiautomatic guns with detachable magazi

Gov. Jared Polis signed a sweeping gun-control measure into law Thursday, the culmination of years of effort by advocates and progressive Democrats to limit the sale of high-powered semiautomatic