A legal monopoly is a market structure in which there is one firm and entry is restricted by the granting of a public franchise, government license, patent, or copyright.

A legal monopoly, statutory monopoly, or de jure monopoly is a monopoly that is protected by law from competition. A statutory monopoly may take the form of a government monopoly where the state owns the particular means of production or government-granted monopoly where a private interest is protected from competition such as being granted exclusive rights to offer a particular service in a specific region while agreeing to have their policies and prices regulated. http://www.investorwords.com/2761/legal_monopoly.html This type of monopoly is usually contrasted with de facto monopoly which is a broad category for monopolies that are not created by government.