|Don’t ask, don’t tell is the common term for the policy about homosexuality in the U.S. military mandated by federal law Pub.L. 103-160 (10 U.S.C. § 654). Unless one of the exceptions from 10 U.S.C. § 654(b) applies, the policy prohibits anyone who “demonstrate(s) a propensity or intent to engage in homosexual acts” from serving in the armed forces of the United States, because it “would create an unacceptable risk to the high standards of morale, good order and discipline, and unit cohesion that are the essence of military capability.” The act prohibits any homosexual or bisexual person from disclosing his or her sexual orientation or from speaking about any homosexual relationships, including marriages or other familial attributes, while serving in the United States armed forces. The “don’t ask” part of the policy indicates that superiors should not initiate investigation of a service member’s orientation in the absence of disallowed behaviors, though mere suspicion of homosexual behavior can cause an investigation.
Quoted from Wiki