The strongest argument against same-sex marriage: traditional marriage is in the public interest

Opponents of same-sex marriage argued that individual states are acting in the public interest by encouraging heterosexual relationships through marriage policies, so voters and legislators in each state should be able to set their own laws.

Some groups, such as the United States Conference of Catholic Bishops, cited the secular benefits of heterosexual marriages, particularly the ability of heterosexual couples to reproduce, as Daniel Silliman reported at the Washington Post.

”It is a mistake to characterize laws defining marriage as the union of one man and one woman as somehow embodying a purely religious viewpoint over against a purely secular one,” the bishops said in their amicus brief. “Rather, it is a common sense reflection of the fact that [homosexual] relationships do not result in the birth of children, or establish households where a child will be raised by its birth mother and father.”

Other groups, like the conservative Family Research Council, warned that allowing same-sex couples to marry would lead to the breakdown of traditional families. But keeping marriage to heterosexual couples, FRC argued in an amicus brief, allows states to “channel the potential procreative sexual activity of opposite-sex couples into stable relationships in which the children so procreated may be raised by their biological mothers and fathers.”

To defend same-sex marriage bans, opponents had to convince courts that there’s a compelling state interest in encouraging heterosexual relationships that isn’t really about discriminating against same-sex couples.

But a majority of Supreme Court justices and most of the lower courts widely rejected this argument, arguing that same-sex marriage bans are discriminatory and unconstitutional.