Held that a private citizen cannot sue one State in the courts of another. Overruled Nevada v. Hall, 440 U.S. 410 (1979), which had held that a State may grant or deny its sister States sovereign immunity as it chooses. The plaintiff here sought to bring a tort suit against a California state agency in Nevada state court. The U.S. Supreme Court concluded that the Constitution barred the suit. Justice Thomas delivered the opinion of the 5-4 Court.