The implementation of any competency testing program must take into consideration the due process clause and the Equal Protection clause of the Fourteenth Amendment. Examples of the violation of the due process clause would be to implement a testing program without adequate notice or to cover material not taught. Instructional validity must be shown, preferably by a formal study by an outside or unbiased agency. The Equal Protection clause is violated when a disproportionate impact due to present effects of past intentional discrimination is shown. Three cases that mark milestones in testing are Griggs v. Duke Power Co., Washington v. Davis, and Debra P. v. Turlington. These three cases show consumers of competency testing for basic skills or occupational skills that documentation of different kinds of validity is necessary. Other cases have challenged the requirement of test passage as a diploma requirement, shown that tests can not be used for a purpose other than that for which they have been validated, and emphasized that tests can not perpetuate the effects of past discrimination. (YLB)