No scientific basis for prohibiting same-sex marriage, key associations argue

"Empirical research demonstrates that the psychological and social aspects of committed relationships between same-sex partners largely resemble those of heterosexual partnerships," the briefs state. "Like heterosexual couples, same-sex couples form deep emotional attachments and commitments. Heterosexual and same-sex couples alike face similar issues concerning intimacy, love, equity, loyalty and stability, and they go through similar processes to address those issues."

Denying recognition to legally married same-sex couples stigmatizes them, according to the "friend of the court" briefs filed in the cases of Hollingsworth v. Perry, which challenges California's Proposition 8, and U.S. v. Windsor, which challenges the federal Defense of Marriage Act. Perry is slated to be argued before the court on March 26; Windsor will be argued on March 27.

The briefs cite empirical scientific evidence that demonstrate that "homosexuality is a normal expression of human sexuality, is generally not chosen and is highly resistant to change." Likewise, "there is no scientific basis for concluding that gay and lesbian parents are any less fit or capable than heterosexual parents, or that their children are any less psychologically healthy and well-adjusted," according to the briefs.

"In drawing conclusions, we rely on the best empirical research available, focusing on general patterns rather than any single study," the briefs state. All the studies cited in the brief were critically evaluated to assess their methodology, including the reliability and validity of the measures and tests employed, and the quality of data-collection procedures and statistical analyses.

APA President Donald N. Bersoff, PhD, JD, noted that the association has a long history of supporting equal access to legal marriage based on years of scientific research. "There is no scientific basis for denying marriage to same-sex couples particularly when research indicates that marriage provides many important benefits," Bersoff said. "The research shows that same-sex couples are similar to heterosexual couples in essential ways and that they are as likely as opposite-sex couples to raise mentally healthy, well-adjusted children."

Joining APA in filing the Windsor and Perry briefs were: the American Academy of Pediatrics; American Medical Association; California Medical Association; American Psychiatric Association; American Psychoanalytic Association; and National Association of Social Workers. Also joining the Windsor brief were: the New York City and New York state chapters of the National Association of Social Workers and the New York State Psychological Association. Also joining the Perry brief were the American Association for Marriage and Family Therapy; the California Chapter of NASW and the California Psychological Association.