The SPUC – a conservative anti-abortion group – are opposed to gay marriage, arguing that government shouldn’t sanction it because there’s no evidence that civil partnerships benefit those involved. Uh, no.
Here’s the American Psychological Association‘s evidenced statement, and here’s another one from the Australian Psychological Society – both arguing that same-sex marriage has mental health benefits, and pointing out the harm caused by social exclusion and discrimination arising from not having the choice to marry.
So, there’s that.