Survey: Why people really oppose gay marriage

Powell acknowledges there is nothing wrong with showing moral disapproval. People have a right to their beliefs and values.

But, if public opinion — either through pressure on lawmakers or directly at the ballot box — drives public policy, Powell’s research suggests that the real motivation for banning same-sex marriage is moral disapproval over homosexuality.

And that, he says, could present a particular challenge for supporters of traditional marriage: Moral disapproval doesn’t make a valid legal case. In fact, same-sex marriage proponents argue that would be unconstitutional.

That’s why the longstanding courtroom debate over same-sex marriage has begun to address a particular legal term: “animus.”