It's become commonplace for religiously affiliated adoption agencies to object to same-sex marriage or civil union bills on the ground that they will be forced to place children in homes with same-sex couples. Of course, if you ask them whether they will support same-sex marriage or civil union if they receive an exemption for adoption placements, they will still say "no." So, really, it becomes a disingenuous way to fight recognition of same-sex couples.
With Illinois about to allow civil unions, such agencies attempted to obtain legislation permitting them to decline to place children with a person in a civil union. Earlier this week, the bill failed in committee by one vote. The Illinois ACLU took the lead in opposing the bill. Its position paper against the bill is very forceful. Read it here. It points out that there is no child welfare basis for such a law and that it amounts to unconstitutional discrimination. One of its other arguments, which I love, is that such a law would send a "cruel and harmful message to gay and lesbian foster children: When you grow up, the agency that provides your care, would never let you take care of other kids."
Almost 15 years ago I wrote an article about the benefit to gay and lesbian children in foster care of openly licensing gay and lesbian foster parents. I don't usually hear that argument made in the political context. Kudos to the Illinois ACLU for making it here.