MEXICO CITY – Mexico's Supreme Court voted Monday to uphold a Mexico City law  allowing adoptions by same-sex couples, drawing jubilant cheers from gay advocacy groups and angry protests from Roman Catholic Church representatives.

The justices voted 9-2 against challenges presented by federal prosecutors and others who had argued the law fails to protect adoptive children against possible ill effects or discrimination, or to guarantee their right to a traditional family.

"Today, institutionalized homophobia has been buried," said Jaime Lopez Vela, a leader of the group Lesbian, Bisexual, Gay, Transsexual and Transgender Agenda. "We are happy, because now we have the same rights and responsibilities of any other married couple."

Monday's decision followed earlier Supreme Court rulings that same-sex marriages performed in Mexico City are constitutional and that other Mexican states must respect them.

Mexico City's groundbreaking same-sex marriage law, enacted in March, extends to wedded gay couples the right to adopt children, to jointly apply for bank loans, to inherit wealth and to be covered by their spouses' insurance policies.

Outside the court building, dozens of gay-rights activists erupted in cheers and chanted "Now we've won!", while a similar number of opponents of the Mexico City law chanted "Man plus woman equals marriage," and "Father, Mother, that's what children need!"

Justices voting with the majority argued that once same-sex marriages had been approved, it would be discriminatory to consider those couples less capable of parental duties than heterosexual couples.

"There is no reliable evidence that sexual orientation determines, by itself" any other type of behavior, said Justice Arturo Saldivar, adding "the preferences of the parents do not determine (a child's) sexual orientation ... that is a discriminatory argument."

But church representatives strongly opposed the ruling.

Father Hugo Valdemar, the spokesman for the Archdiocese of Mexico, said the court had "treated children as if they were pets, to be adopted by whoever wants one, and that violates their rights."

Armando Martinez, the leader of the Catholic Lawyers' Association, said his group will ask for the impeachment of the justices who voted to uphold the Mexico City law, adding "the justices are not God. They make a lot of mistakes."

Three hundred and thirty-nine gay and lesbian couples have married under the law, but city officials say none of those couples have yet applied to adopt children.

Lopez Vela said his group expects to present the first such application next week, on behalf a lesbian couple.

But the already difficult process of adoption in Mexico — it usually involves years of red tape, and orphans here are usually adopted by a relative anyway — make it unlikely that same-sex adoptions of unrelated children will ever be numerous.

For example, Lopez Vela said the first application would involve the adoption of a girl by the lesbian partner of the child's biological mother.

Justices who sided with the majority stressed that potential adoptive parents, gay or straight, are checked for suitability as part of the adoption process.

"It is not a question of sexuality that determines whether a person is qualified or not to adopt," said Justice Margarita Luna.

The Roman Catholic Church heatedly opposed the law, and the court voted unanimously Monday to condemn comments by Cardinal Juan Sandoval, the archbishop of Guadalajara, who suggested over the weekend that justices may have been paid off by the Mexico City government to favor the law.

Mexico City's law was the first of its type in Latin America when it was enacted.

Argentina became the first country in the region to permit gay marriage in July, when President Cristina Fernandez signed legislation declaring that wedded gay and lesbian couples have all the same legal rights and responsibilities as heterosexual couples, including the right to inheritance and to jointly adopt children.