Section 3 of DOMA merely clarifies that federal policy is to make certain benefits available only to those persons united in heterosexual marriage, as opposed to any other possible relationship defined by law, family, or affection.  As a result, gay and lesbian individuals who unite in matrimony are denied no federal benefits to which they were entitled prior to their marriage; they remain eligible for every benefit they enjoyed beforehand.  DOMA simply provides, in effect, that as a result of their same-sex marriage they will not become eligible for the set of benefits that Congress has reserved exclusively to those who are related by the bonds of heterosexual marriage.

–Brief filed by the DOJ in its defense of the so-called Defense of Marriage Act.