After considering the implications of workplace substance-abuse testing for employees' privacy rights, the article focuses on how handicap and discrimination laws may restrict employer substance-abuse testing programs. Following consideration of collective bargaining agreements' impact on employee drug testing, criteria for effective substance-abuse testing programs in both the public and private sectors are suggested. Criteria for a public employer's drug testing program that would likely withstand judicial scrutiny must show a legitimate state interest in such testing (a safe working environment and the public welfare), be based on reasonable suspicion that the person being tested is abusing drugs, and be accompanied by tests for other medical conditions that could impair safe job performance. Public employer drug testing should also be conducted pursuant to a written, published policy; involve knowing and voluntary consent to testing by each employee; contain safeguards to ensure reliable chain of custody for test samples; use a reputable laboratory for specimen analysis; and ensure that test results are confidential. Criteria for private employer drug testing programs generally parallel those for public employers, but the criteria may be more liberal in the use of testing absent reasonable suspicion of drug use. 145 footnotes.