"Don't ask, don't tell" (DADT) was the official United States policy on military service of non-heterosexual people, instituted during the Clinton administration. The policy was issued under Department of Defense Directive 1304.26 on December 21, 1993, and was in effect from February 28, 1994, until September 20, 2011. The policy prohibited military personnel from discriminating against or harassing closeted homosexual or bisexual service members or applicants, while barring openly gay, lesbian, or bisexual persons from military service. This relaxation of legal restrictions on service by gays and lesbians in the armed forces was mandated by Public Law 103–160 (Title 10 of the United States Code §654), which was signed November 30, 1993. The policy prohibited people who "demonstrate a propensity or intent to engage in homosexual acts" from serving in the armed forces of the United States, because their presence "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 prohibited any non-heterosexual person from disclosing their sexual orientation or from speaking about any same-sex relationships, including marriages or other familial attributes, while serving in the United States armed forces. The act specified that service members who disclose that they are homosexual or engage in homosexual conduct should be separated (discharged) except when a service member's conduct was "for the purpose of avoiding or terminating military service" or when it "would not be in the best interest of the armed forces". Since DADT ended in 2011, persons who are openly homosexual and bisexual have been able to serve.
The "don't ask" section of the DADT policy specified that superiors should not initiate an investigation of a service member's orientation without witnessing disallowed behaviors. However, evidence of homosexual behavior deemed credible could be used to initiate an investigation.