In the United States such professional organizations as the American Psychiatric Association, American Psychological Association, American Sociological Association, American Anthropological Association, American Medical Association, American Academy of Pediatrics, American Academy of Nursing, and National Association of Social Workers have said that claims that the legal recognition of marriage for same–sex couples undermines the institution of marriage and harms children are inconsistent with the scientific evidence which supports the conclusions: that homosexuality is a normal expression of human sexuality that is not chosen; that gay and lesbian people form stable, committed relationships essentially equivalent to heterosexual relationships; that same-sex parents are no less capable than opposite-sex parents to raise children; that no civilization or viable social order depends on an institution of exclusive heterosexual marriage; and that the children of same-sex parents are no less psychologically healthy and well-adjusted than children of opposite-sex parents.[119][120][121][122][123][124][125][126] The body of research strongly supports the conclusion that discrimination by the federal government between married same-sex couples and married opposite-sex couples in granting benefits unfairly stigmatizes same-sex couples. The research also contradicts the stereotype-based rationales advanced to support passage of DOMA that the Equal Protection Clause was designed to prohibit.[127]
The 2012 Democratic Party Platform used the term "marriage equality" in its expression of support.[128]