I have argued for most of the last decade or more that all laws banning same-sex marriage, or reducing same-sex marriage to the level of civil unions, is a violation of the Establishment Clause in the U.S. Constitution (the separation of church and state). These laws are founded in and argued from a distinctly Christian framework, which is in essence establishing a state religion (any encoding of religious beliefs in law by the government can be seen as a violation of the Establishment Clause).
I have never seen a legal expert make this argument, so I thought I would share this article from Eric Yordy, Associate Dean and Assistant Professor, The W.A. Franke College of Business, Northern Arizona University (Yordy has a J.D. from Cornell Law School).
The W. A. Franke College of Business
February 5, 2013
22 Tul. J.L. & Sexuality 55, 2013
This article addresses the conflict between marriage as a religious concept and marriage as a legal concept. It analyzes the "establishment" of religion when government defines marriage.
Yordy, Eric D., Caught in the Clause: An Analysis of Same-Sex Marriage Through the Lens of the Establishment Clause (February 5, 2013). 22 Tul. J.L. & Sexuality 55, 2013. Available at SSRN: http://ssrn.com/abstract=2278641
... At the federal level, the Defense of Marriage Act was passed into law in 1996, giving states the ability to refuse to recognize same-sex marriages performed in other states and defining marriage as a union between a man and a woman for all federal purposes. ... Because the religion clauses do focus on the term "religion" rather than "moral belief" or simply "belief," Professor Choper uses the after-life consequences as the sole factor to separate religious beliefs from other beliefs. ... Goodsell, early Christian churches sanctioned and accepted existing nonchurch marriages. ... And like the MCC churches, the UUA seems to be a legitimate religion under the Brimmer test. ... Justice Thomas concurred in the opinion but argued that the Establishment Clause should not even be a consideration for two reasons: (1) the Establishment Clause was never meant to apply to the states but only to the federal government, and (2) even if the clause applies to the states, there is nothing about this display that coerces a person to view the display. ... Applying this idea to the marriage definition question, the precise argument of many religious leaders is that a civil definition of marriage that includes same-sex couples will lead to coercion to perform those marriages or lose government benefits (such as tax exempt status). ... Applying a two-prong Lemon test, where excessive entanglement and effect are analyzed together, we see that civil marriage definitions still fail the test - in large part due to the tremendous effect of advancing traditional religion over legitimate, nontraditional, religion or nonreligion. ... Conclusion: Given that marriage is primarily a religious concept, or at least is a primary and defining concept in many religions, it is a violation of the Establishment Clause of the United States Constitution for the government to be involved in defining religion.