(AP) -- A Columbia University social scientist says California's voter-enacted ban on same-sex marriages contributed to the social stigma that makes gay men and lesbians more susceptible to depression, suicide and substance abuse.
Testifying in the federal trial to decide if Proposition 8 violates the U.S. Constitution, Ilan Meyer said the measure sent a message of "You are not welcome here" to gay people by erecting a barrier to a "desirable and respected" institution.
"People in our society have goals that are cherished by all people, that are part of the social convention," Meyer said. "We are all raised to think there are certain things we want to achieve in life, and this Proposition 8 says if you are gay or lesbian, you cannot achieve this particular goal."
The trial, the first in a federal to examine the constitutionality of state gay marriage bans, is scheduled to resume Friday with testimony from Michael Lamb, a Cambridge University psychologist who will discuss gay and lesbian parenting and the benefits to children of allowing same-sex couples to marry.
During Thursday's session, Howard Nielson Jr., a lawyer for the measure's sponsors, mounted an exhaustive cross-examination, using Meyer's own research showing that black and Latino gays had fewer mental health problems than white gays to try to undercut the professor's assertion. Meyer had hypothesized in his study that black and Latino gays would have more mental health issues because of their dual minority identities.
Nielson also challenged Meyer on his statement that California's domestic partnership law, which grants same-sex couples the same legal benefits and responsibilities as married spouses, was itself a source of stigma and emotional distress. Equality California, the state's largest gay rights group, sponsored the 2003 law.
"Do you believe Equality California would sponsor legislation that would stigmatize (gay) individuals," Nielson asked.
"No, but that doesn't change my answer," Meyer said. "Having a second type of an institution that is clearly not the one that is designed for most people clearly is stigmatizing."
Earlier Thursday, an economist for the city of San Francisco testified that preventing gays from getting married costs the city millions of dollars a year in lost revenue and increased services.
Explore further: Study finds law dramatically curbing need for speed