The Supreme Court’s ruling Thursday that Americans have a right to carry a handgun outside the home for self-defense — striking down a New York law that made it illegal to carry a gun in public without proving there was a special need for protection — could mean Maryland will have to change its own similar law. Under state law, a gun owner must prove that they have a “good and substantial reason” to carry a concealed weapon. That could include proving they have been threatened and are in danger, showing they have high security clearances, or being a business owner. About 39,000 concealed carry licenses are issued in Maryland.