The statute placing Amendment 1 on the ballot, and the amendment itself, both violate the Establishment Clause of the First Amendment to the U.S. Constitution. The Constitution guarantees that "Congress shall make no law respecting the establishment of religion." This prohibition applies to the states as well as Congress. In evaluating whether a law establishes religion, courts require that the law has a "secular purpose," that its "primary effect" "neither advances nor inhibits religion," and that it does not cause "excessive entanglement" of government and religion.
Proponents of Amendment 1 have offered nothing but religious justifications for the amendment and no valid secular purpose. Some legislators are on record as justifying the amendment based on the religious arguments. Even if they could convince anyone that the amendment's primary purpose is secular, it is also clear that the amendment's primary effect is to both advance and inhibit religion: It advances conservative Christian beliefs by codifying those Christians' definition of marriage, while it inhibits the free exercise of others' religions by denying churches that believe in marrying same-sex couples the opportunity to do so in legally recognized fashion. And what could more excessively entangle government with religion than adopting and elevating one religious group's definition of marriage and imposing it on everyone else?
The Iowa Supreme Court is, as yet, the only court to use Establishment Clause analysis to overturn a same-sex marriage ban, in Varnum v. Brien. Equal-protection arguments are strong and important, but anti-amendment lawyers should also sharpen their First Amendment arguments if this deplorable amendment passes.