As a result of the great number of airborne hijackings and in an attempt to prevent them, the United States Government has developed a "system for discouraging and apprehending potential hijackers" that includes the use of a metal detecting device known as a magnetometer. The constitutional validity of the use of this device recently has been questioned in regard to the fourth amendment right against unreasonable searches and seizures in the case of Epperson v. United States.