Writing at the Volokh Conspiracy, Dale Carpenter, a thoughtful and fair minded proponent of same sex marriage, comments on the "religious liberty" objection to SSM. That objection, most prominently pushed by Maggie Gallagher, was restated in a column on NRO earlier this week.
Carpenter, a lawprof at Minnesota, argues that many of the recent examples cited by SSM opponents as examples of SSM impinging upon religious liberty, involved the application of general antidiscrimination laws and some occurred in states where SSM marriage is not recognized. In Carpenter's view, the pressure on religious liberty (to which he is sympathetic) stems from the general movement toward nondiscrimination on the basis of sexual orientation. There is a great deal of merit in his argument.
Dan Markel, writing at Prawfsblawg (where yours truly will take a guest turn in December)picks up on Professor Carpenter's post and argues for a fairly broad (but not unlimited)principle of nondiscrimination anchored in Professor Markel's view that "in almost all cases, sexual orientation is about as morally irrelevant as the race of a person."
I think that Professor Markel's principle illustrates the weakness in Professor Carpenter's suggestion that SSM does not extend the principle of nondiscrimination in significant ways. Let's use the the case of Catholic Charities in Boston as an example. It was essentially run out of the adoption business because it would not place children with same sex couples. Professor Markel thinks that this was the right result while Professor Carpenter would have granted them an exemption.
But SSM marriage does affect the way in which we think about the application of the nondiscrimination principle to Catholic Charities. I may believe (in fact I do) that gay and lesbian persons ought not to be discriminated against in a variety of contexts.
But I may still view marriage as an institution that requires man and a woman because it is a cultural and legal response to the particulars of male-female sexual attraction, the fact that it makes children and the belief that, all things equal, it is preferable for children to be raised by their biological parents living together. In this view, what is relevant is not so much sexual orientation but gender. I may reasonably conclude that my opposition to SSM marriage is not so much discrimination on the basis of sexual orientation but a judgment that marriage requires the union of a man and a woman. That belief may well be rooted in religious belief (see, e.g., Roman Catholic teaching on the complementarity of the sexes)- although, in my case, I am powerfully committed to secular arguments.
SSM, if widely accepted, undercuts that argument because it denies the relevance of gender to marriage. It extends the principle of nondiscrimination and leads us to Professor Markel's view that sexual orientation is almost always irrelevant.