Animus-based invalidation of really old man-woman marriage laws

I guess I should have been reading blog posts instead of law review articles. A little earlier today, Dale Carpenter published a Volokh Conspiracy post criticizing one part of Judge Sutton's rational basis analysis in DeBoer v. Snyder. The first link in that post is to an earlier VC post by Professor Carpenter about a district court decision holding unconstitutional a Michigan law prohibiting localities from extending benefits to employees' same-sex domestic partners. And that earlier post includes a discussion about the scope of animus-based arguments against legal definitions of marriage as the union of one man and one woman. After identifying five factors for an animus analysis (textual, contextual, procedural, effectual, and pretextual) and contending that they show the unconstitutionality of the state constitutional amendments that "constitutionalized marital definitions of the first time," Professor Carpenter turns to the marriage statutes that preceded these amendments. He writes: 

Even the remaining exclusion of same-sex couples from marriage reflected in longstanding state statutes may be vulnerable to animus attacks based on the other objective factors noted above. It can hardly escape notice that states have consciously and steadfastly refused to include same-sex couples in their marriage statutes, in addition to specifically excluding them through anti-SSM state constitutional amendments and through state "mini-DOMAs" that deny all recognition to married same-sex couples from out of state. A failure to include, as well as an affirmative act to exclude, may also reflect animus against a class. That is at least a question the Supreme Court may now consider.

If animus-based invalidation extends to encompass statutory definitions from the late-eighteenth and early-nineteenth century, then the remedial question asked in my prior post has an easy answer. The remedy for animus-based invalidation of state constitutional amendments defining marriage as the union of one man and one woman cannot be a return to the status quo ante because that status quo was also unconstitutional.

This expansive understanding of animus seems to present problems of its own. For example, Professor Carpenter describes animus analysis as a type of purpose-based constitutional test. But it would not have been possible to form the purpose to exclude same-sex couples from marriage at least until it was possible to conceive of marriage as potentially including same-sex unions. That may be why Professor Carpenter focuses on conscious and steadfast refusal to expand marriage definitions, which in turn would seem to raise a state action problem. In any event, I wanted to link to Professor Carpenter's posts because they contained one answer to the question asked in my last post.