United Nations Convention on the Rights of Persons with Disabilities. Last December, the Senate voted down ratification, mainly because a significant number of Republican Senators either felt or were convinced to feel that the UN convention would have unintended consequences, mostly for parents of children with disabilities.
Specifically, a handful of conservative groups claimed that the convention would threaten parental authority and home schooling, citing a line stating that "the best interests of the child shall be a primary consideration" in whether the rights of children with disabilities are being respected.
I've started reading the convention from start to finish, and when I'm done, I'll write more if I have anything to add. My initial sense is that objections to this disability rights convention isn't about the convention itself; most of the people who oppose it oppose the United Nations itself, and many of them have a massively inflated conception of the UN's practical power.
As I read, it also seems like there are many, many more sections and provisions that would help preserve family rights and protect family integrity … that should, in fact, appeal even more strongly to conservatives than to progressives.
Finally, I really think that with UN human rights initiatives, you have to think in terms of countries where traditions and practices may be very, very different from ours. We think we're divided on moral, family, and sexual values here in the US, but compared with the world at large, conservatives and liberals here in the US are actually pretty much on the same page. I'm not saying we are vastly more moral or ethical in the US or "The West", but I do think that the disability rights standards in the UN convention are far, far more of a practical challenge in some countries and cultures than to American society.
So yeah, more specifics to come.