The English rule as to the parties to an action was that all persons could sue or be sued with the exceptions that felons, outlaws, and alien enemies could not sue, and the sovereigns, foreign states and ambassadors could not be sued.

The American rule is that all persons have legal capacity to sue or be sued. An alien enemy suing will not be heard during the continuance of the war, and a political sovereignty can be sued by a private person only with its own consent.1