WASHINGTON—The Supreme Court ruled for the first time that gun possession is fundamental to American freedom, giving federal judges power to strike down state and local weapons laws for violating the Second Amendment. In a 5-4 ruling, the court held that the Second Amendment's right to keep and bear arms is a fundamental right that binds states. "Self defense is a basic right, recognized by many legal systems from ancient times to the present day," wrote Justice Samuel Alito. He was joined in reaching the result by Chief Justice John Roberts and justices Anthony Kennedy, Antonin Scalia and Clarence Thomas....