Much of the debate on same-sex marriage has focused on the rights and morality of adults. Supporters of marriage equality argue gays and lesbians should be allowed to marry the person they love to have equal access to the many government benefits obtained through a legally recognized marriage. Opponents say that prohibiting same-sex marriage discourages homosexuality and somehow incentivizes opposite-sex marriage, which they see as better and even necessary for procreation.
What's missing from this debate, Pollvogt and Smith argue, is how prohibiting same-sex couples from marrying effectively punishes the children in order to punish parents. In the past, the Supreme Court has opposed laws with those types of effects on children, the authors point out:
Punishing children for matters beyond their control is patently impermissible as a matter of Supreme Court precedent regarding the constitutional rights of children. In the first of these cases, the court considered a Louisiana law that forbade children born out of wedlock from receiving benefits upon the wrongful death of their mother. Louisiana argued that the law was a perfectly legitimate means of expressing moral disapproval of extramarital liaisons. The Supreme Court, however, determined that the law violated equal protection because it is fundamentally unfair and irrational for a state to deny important benefits to children merely to express moral disapproval of the conduct of adults—or to incentivize adults to behave in a particular way.
In a similar case decided several years later, the court addressed another Louisiana statute that intentionally disadvantaged children born out of wedlock. Specifically, the law at issue preferred "legitimate" children to "illegitimate" children in distributing worker’s compensation benefits upon the death of a parent. The court invalidated the statute, holding that, under the equal protection clause, both classes of children must be permitted to recover equally. "No child," the court wrote, "is responsible for his birth and penalizing the illegitimate child is an ineffectual—as well as unjust—way of deterring the parent."
In yet another case decided a decade later, the court relied on the same logic in holding that states could not constitutionally deny public education to undocumented immigrant children in an effort to discourage their parents from entering the country illegally. The constitutional conclusion from this line of cases is clear: No matter how reprehensible a state finds certain adult conduct, it cannot curb that conduct through laws that punish children.
These cases largely referenced legal marriages that are already on the books. When the Supreme Court struck down the Louisiana laws, they didn't expand marriage rights, as a decision in a same-sex marriage case could; the court instead empowered unwed parents and their children.
Still, the courts have cited marriage's benefits for children in previous same-sex marriages. Justice Anthony Kennedy, who's widely expected to act as the deciding swing vote when the Supreme Court rules on marriage equality, cited the children of same-sex couples in his decision that struck down the federal ban on same-sex marriage. Kennedy wrote that stigmatizing same-sex marriage "humiliates tens of thousands of children now being raised by same-sex couples. The law in question makes it even more difficult for the children to understand the integrity and closeness of their own family and its concord with other families in their community and in their daily lives."
Kennedy's point is backed by some of the research into the issue. One study found the children of same-sex parents can be happier than the rest of the population. But another study concluded that prohibiting the children's parents from getting married could actually inhibit their developmental outcomes.