Patricia Cain (Santa Clara) has published DOMA and the Internal Revenue Code, 84 Chi-Kent L. Rev. 481 (2009).  Here is the abstract:

The Defense of Marriage Act (DOMA) prohibits the recognition of same-sex marriages for any purpose under federal tax law. The primary justification for this rule is that tax benefits should be preserved for opposite-sex married couples. This article points out the absurdity of such a rule, given that tax law is not intended to privilege married couples, but instead is intended to measure their taxable income fairly on the basis of their status as related parties. Because the justification fails, DOMA as applied to federal tax law is unconstitutional.