William Haun, a lawyer in DC, makes the limited government case against gay marriage:
"...A society where marriage is divorced from its procreative purpose within a stable union is a society that neuters its ability to prevent predatory men from impregnating women and abandoning them and to ensure that men take responsibility for their offspring. And it denies the child an incontrovertible social benefit: a present mother and father.
In such an alternative society—where marriage is divorced from procreation—the government steps in to look after children and relationships. And why not? If same-sex advocates view government validation of relationships as the means to achieve their social legitimacy, why not also look to government to solve the social failings of relationships?
Ultimately, the argument for same-sex marriage attempts to appeal to the personal promises we husbands and wives make to each other. But it only uses this course of reasoning because it cannot appeal to society’s reasons for establishing marriage laws in the first place. Yet when debating whether or not to license something, we cannot let our emotions determine the extent of government power. Government power that lacks a logical limiting principle—as the argument for same-sex marriage does—is inconsistent with limited government. To support limited government is to support traditional marriage." -- First Things