A law took effect yesterday that makes it illegal for most employers to use the controversial polygraph for pre - employment screening , or against workers already on the payroll . It is estimated that the law will ban 80 percent of the two million polygraphs administered annually . The law will have its greatest impact in those states that have no laws banning or restricting its use . It is now illegal across America for most employers in interstate commerce to use the controversial polygraph for pre-employment screening purposes or to use them randomly against workers already on their payroll. Firms providing armored cars , security alarms and security guards are exempt , as are companies that manufacture and distribute controlled substances . The law does not apply to local , state and federal employees , and to firms doing sensitive work for the government
A law took effect yesterday that makes it illegal for most employers to use the controversial polygraph for pre - employment screening , or against workers already on the payroll . It is estimated that the law will ban 80 percent of the two million polygraphs administered annually . The law will have its greatest impact in those states that have no laws banning or restricting its use . Firms providing armored cars , security alarms and security guards are exempt , as are companies that manufacture and distribute controlled substances . The law does not apply to local , state and federal employees , and to firms doing sensitive work for the government