Under the rational basis test, Mr. Clement said, Congress could have acted rationally "in the face of the unknown consequences of a proposed novel redefinition of the foundational social institution," and it could have acted rationally to "protect the public fisc" in the balance it strikes in allocating federal burdens and benefits, and providing "consistency in eligibility for federal benefits based on marital status."

Congress also could have acted rationally "to avoid creating a social understanding that begetting and rearing children is not inextricably bound up with marriage" and to "foster marriages that provide children with parents of both sexes."

Finally, Mr. Clement states "any redefinition of marriage should be left to the democratic process."