Workplace testing for drug use is constitutionally impermissible, with two exceptions: (1) employers may use drug testing as a device to screen out prospective employees; and (2) employers may use involuntary workplace drug testing to help employees become drug free, so long as no further sanctions are involved. There are very few acceptable grounds for abrogating or limiting constitutional rights; mostly they relate to the US Supreme Court's clear and present danger criteria or the ranking of one constitutional right over another. In the absence of hard evidence that drug use impairs work performance and causes avoidable social ills, attempts to abrogate any constitutional guarantee will not likely succeed. Of course, should workers accept employment in workplaces with prior existent drug-free rules, they have voluntarily submitted to those rules, possibly including drug testing, and the explicit sanctions attached to them. References