Unlike public sector employers, private organizations are not bound by constitutional restraints that prohibit substance abuse testing. Similarly, nonunion organizations do not have to justify their right to test employees. However, legal issues in the public sector are not yet firmly defined. While several States have constitutionally expressed a right to privacy, case law has not tested this position; reasonable suspicion or compelling need would probably override this type of provision. Other constitutional rights, such as privacy, equal protection, and protection from self-incrimination do not prohibit testing but do require a legitimate concern and fair guidelines to protect employee rights. Unionization clearly affects the legal issues surrounding substance abuse testing. While the National Labor Relations Board (NLRB) has taken no definitive position, a former General Counsel has stated that a drug testing program is a mandatory subject of collective bargaining under the National Labor Relations Act (NLRA) when such testing becomes a condition of employment. Mandatory testing must also be negotiated when it is added to an existing program of mandatory physical examinations for employees or applicants. Although a union may waive its right to bargain by contract, past practice, or inaction, such waiver must be "clear and unmistakable." Injunctive relief against an employer would be warranted if a highly invasive, random, or universal drug testing program were implemented unlawfully. The scope of bargaining includes the content, purpose, and disciplinary effect of the testing; however, employers are bound only to bargain in good faith until agreement or impasse at which point the program or policy will be implemented. 49 footnotes.