Security Clearances: Consideration of Sexual Orientation in the Clearance Process, Report to the Congressional Requesters [open pdf - 3MB]
"Federal agencies used the sexual perversion criteria in the early 1950s to categorize homosexuals as security risks and separate them from government service, Agencies could deny homosexual men and women employment because of their sexual orientation until 1975, when the Civil Service Commission issued guidelines prohibiting the government from denying employment on the basis of sexual orientations3 The guidelines, which further define the provisions of Executive Order 10450, resulted from court decisions requiring that persons not be disqualified from federal employment solely on the basis of homosexual conduct. Although the public policy change resulted in the restrictions against employment of homosexuals being lifted, the guidance for granting security clearances to homosexuals remained generally vague or restrictive until the early 1990s. Appendix 11 contains a synopsis of key court decisions pertaining to sexual orientation and the security clearance process."
Government Accountability Office (GAO): http://www.gao.gov/