The principles of disparate or unequal treatment must be distinguished from the concepts of validation. A selection procedure--even though validated against job performance in accordance with these guidelines--cannot be imposed upon members of a race, sex, or ethnic group where other employees, applicants, or members have not been subjected to that standard. Disparate treatment occurs where members of a race, sex, or ethnic group have been denied the same employment, promotion, membership, or other employment opportunities as have been available to other employees or applicants. Those employees or applicants who have been denied equal treatment, because of prior discriminatory practices or policies, must at least be afforded the same opportunities as had existed for other employees or applicants during the period of discrimination. Thus, the persons who were in the class of persons discriminated against during the period the user followed the discriminatory practices should be allowed the opportunity to qualify under less stringent selection procedures previously followed, unless the user demonstrates that the increased standards are required by business necessity. This section does not prohibit a user who has not previously followed merit standards from adopting merit standards which are in compliance with these guidelines; nor does it preclude a user who has previously used invalid or unvalidated selection procedures from developing and using procedures which are in accord with these guidelines.