The U.S. Supreme Court has unanimously blocked a $10 billion lawsuit filed by Mexico against major U.S. gun manufacturers, including Smith & Wesson, Beretta, Glock, and Colt. Mexico accused the companies of fueling cartel violence by knowingly allowing firearms to be trafficked into the country. But the justices ruled the gunmakers are shielded under U.S. law, which largely protects them from liability when their weapons are used in crimes.