Amicus briefs filed with the U.S. Supreme Court by the American Psychological Association and other groups said denying recognition to legally married same-sex couples stigmatizes them.
The "friend of the court" briefs were 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.
"Empirical research demonstrates the psychological and social aspects of committed relationships between same-sex partners largely resemble those of heterosexual partnerships," the briefs stated. "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."
The briefs cite empirical scientific evidence that demonstrates "homosexuality is a normal expression of human sexuality, is generally not chosen and is highly resistant to change."
"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," the briefs said.
Joining the APA in filing the Windsor and Perry briefs were the American Academy of Pediatrics, the American Medical Association, the California Medical Association, the American Psychiatric Association, the American Psychoanalytic Association and the 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 National Association of Social Workers and the California Psychological Association.
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