This paper attempts to find a path through the recent constitutional thicket regarding same sex marriage by analogizing marriage to a business association. This analogy provides a way to evaluate the justifications for traditional rules banning same sex marriage -- specifically, by emphasizing the advantages of providing distinct standard forms for different types of relationships. Under this approach, the same sex marriage prohibition might be justified by the need to preserve the precise boundaries of the marriage standard form. The business association analogy also highlights what is at stake in state laws prohibiting same sex marriage, and therefore helps determine the appropriate burden to impose on defenders of the prohibition. Like business associations, the validity of a marriage generally is governed by the law of the state in which the marriage is celebrated. This offers the potential of allowing couples, including same sex couples, to select not only from among the standard forms in a particular state, but also from the menus of standard forms offered by various states. This analysis helps assess the infringement on liberty involved in a state's prohibition of same sex marriage. Moreover, as with business associations, permitting the interstate market for standard forms to operate would provide an evolutionary approach to marriage laws that is preferable to the Court's prematurely taking sides in the marriage debate.