Although the Fourth Amendment protects the privacy rights of citizens from government intrusion, the private sector has traditionally had much less restriction. By 1985 urine-testing was a $100 million business. Twenty-five percent of the Fortune 500 corporations had some kind of urine-testing program in place. Companies like Federal Express fired employees on the basis of a single positive drug test despite a federal survey that found such testing procedures to be in error at least twenty percent of the time. According to government figures the percentage of false-positive results at many labs was much higher.