Cato’s Robert Levy argues that it is, in The moral and constitutional case for a right to gay marriage. He argues:
Thomas Jefferson set the stage in the Declaration of Independence: “[T]o secure these Rights, Governments are instituted among Men.” The primary purpose of government is to safeguard individual rights and prevent some persons from harming others. Heterosexuals should not be treated preferentially when the state carries out that role. And no one is harmed by the union of two consenting gay people. … Whenever government imposes obligations or dispenses benefits, it may not “deny to any person within its jurisdiction the equal protection of the laws.” That provision is explicit in the 14th Amendment to the U.S. Constitution, applicable to the states, and implicit in the Fifth Amendment, applicable to the federal government.
I’m skeptical of the validity of the legal arguments being appealed to here, and also to the wisdom of trusting the central state for protection of individual rights. As to the former, it seems far-fetched to believe that Jefferson or other Founders believed the Declaration or Constitution to enshrine a right to gay marriage, or to things like sodomy or miscegenation (re sodomy, see my Supreme Confusion, Or, A Libertarian Defense of Affirmative Action). After all, slavery was legal, Jefferson was a slaveowner, and sodomy was not looked on kindly [update: see Jefferson's A Bill for Proportioning Crimes and Punishments, proposing "Whosoever shall be guilty of Rape, Polygamy, or Sodomy with man or woman shall be punished, if a man, by castration, if a woman, by cutting thro' the cartilage of her nose a hole of one half inch diameter at the least"]. This is not to justify these odious views, but rather to recognize that the Founders were not libertarian, contra Randian mythologizing. As for the Equal Protection Clause of the Fourteenth Amendment, again, it seems unlikely the the Framers and ratifiers of that amendment, in the late 1860s, interpreted it so broadly as to protect such rights. After all, if the Equal Protection Clause were so broad, why wouldn’t it have prohibited discrimination against blacks and women in voting? Obviously, it didn’t, since these had to be provided for in subsequent amendments to the Constitution (the 15th and 19th). The Fourteenth Amendment and its Equal Protection Clause were obviously not as broad as some modern libertarian centralists might like. It it was not broad enough to prevent the blatant racial and sexual discrimination in voting law, it’s ludicrous to suggest it was broad enough to cover the very modern idea of gay marriage and to prohibit treating it differently from heterosexual marriage.
As for the latter point, about the strategic wisdom of relying on the central state for protection of individual rights–it is futile to expect a paper Constitution, construed by the state, to serve as a significant and effective limit of that state. Indeed, as Hoppe has argued, the Constitution served as a means of expansion of state power. This is not surprising, given the nature of the state. As Hoppe observes (in Reflections on State and War):
the state is defined as an agency with two unique characteristics. First, it is a compulsory territorial monopolist of ultimate decision-making (jurisdiction). That is, it is the ultimate arbiter in every case of conflict, including conflicts involving itself. Second, the state is a territorial monopolist of taxation. That is, it is an agency that unilaterally fixes the price citizens must pay for its provision of law and order. … Predictably, if one can only appeal to the state for justice, justice will be perverted in favor of the state.
the government is the ultimate judge in every case of conflict, including conflicts involving itself … instead of merely preventing and resolving conflict, a monopolist of ultimate decision-making will also provoke conflict in order to settle it to his own advantage. That is, if one can only appeal to government for justice, justice will be perverted in the favor of government, constitutions and supreme courts notwithstanding. Indeed, these are government constitutions and courts, and whatever limitations on government action they may find is invariably decided by agents of the very same institution under consideration. Predictably, the definition of property and protection will be altered continually and the range of jurisdiction expanded to the government’s advantage. The idea of eternal and immutable law that must be discovered will disappear and be replaced by the idea of law as legislation – as flexible state-made law.
Hoppe, The Idea of a Private Law Society. (See also Hoppe, On the Impossibility of Limited Government and the Prospects for a Second American Revolution; and Anthony de Jasay, Against Politics, pp. 5, 19, 22, and ch. 2 et pass., discussing the impossibility of limited government when the state itself construes its own authority, as discussed in my review of same on pp. 86-87.)
Similarly, as J.H. Huebert writes in Book Review of Restoring the Lost Constitution: The Presumption of Liberty by Randy E. Barnett:
Mr. Barnett’s well-reasoned and well-supported arguments for a limited federal government make up a large portion of the book, but I make short shrift of them here because, despite their appeal, they are almost entirely useless. The Ninth Amendment and the Commerce Clause are not, as he says, “lost”—they have been in the Constitution all along. Courts have distorted these provisions not because judges have not had Randy Barnett to explain their true meaning. Courts have done so because they are part of the very federal government Randy Barnett seeks to limit. In general, judges and those who appoint them have no reason to want to limit government. … Have not judges been responsible for some of the most outrageous expansions of government power? And, after all, are judges not a product of the same political system that gives us legislators and presidents? What president would appoint judges who would tell him he cannot do anything he wants? What Senators would confirm a judicial candidate who tells them that everything they have ever done in office is unconstitutional? The whole enterprise of libertarian constitutional theory ignores all we have learned from public choice economics about the incentives of government actors.
(See also Barnett’s response, Libertarianism and Legitimacy: A Reply to Huebert, and Huebert’s rejoinder, No Duty to Obey the State: Reply to Barnett. For more skepticism of centralizing state power in the vain hope of protecting individual rights, see The Libertarian Case Against the Fourteenth Amendment; Barnett and the Fourteenth Amendment; Randy Barnett’s Proposed “Federalism Amendment”; The Unique American Federal Government; Libertarian Centralists; To Hell with Heller; also More on Kelo and Federalism, and Doherty on Kelo.)
Levy has a point about the morality of this issue, however. I’ve set forth my thoughts on this before in The Libertarian Case for Gay Marriage. The basic idea is this. There should be no state. In a stateless world, marriage would be just one of many voluntary relationships, with contractual aspects. The contractual aspects would be recognized and given effect by the private legal system(s). People could refer to various relationships by whatever words they wanted, and other people would be free to respect, or sneer, at the “legitimacy” of others’ relationships. And even if there is a state, there is no need for it to decree and regulate marriage. If it is going to monopolize the legal system, it can give effect to contracts and consensual arrangements without “blessing” the relationship to which the contractual aspect pertains.
But the state has not done this. It has not only coopted the legal system–in taking on the role of defining, approving, regulating, and licensing the status of marriage itself, it has stated that it will give effect to the contractual regime (hospital visitation rights, coownership, medical power of attorney, default inheritance rules, etc.) accompanying a romantic (or other) relationship only if it qualifies as “marriage” as the state defines it; and then the state restricts marriage to heterosexual couples. I.e, it is the state that says “it must be ‘marriage’ for us to recognize contractual aspects of your relationship. If it’s not ‘marriage’ (as we define it), then we do not recognize it.” This is what the state has no right to do: they force you to pay for and be subject to their legal system; they outlaw competition; and then they tell you that this system will not honor your contractual arrangements. This is the same as banning or penalizing the behavior you are trying to contract about, and the state has no right to do this. The state must recognize and enforce the contractual regime set up by free individuals, if it is going to coopt that field. Now, if the state simply said, “call it a ‘civil union,’ and we’ll recognize it,” then the gay marriage advocates would have no complaints. But so long as the state continues to insist that only “state-approved-marriage” will be able to protect its contractual aspects in the legal system, so long as the state coopts the courts and the contract-enforcement system, then they have no right to exclude people from that protection. If “marriage” is the only legal classification for which the state will recognize civil effects of a relationship, then the state must allow gay relationships (or any kind of relationship–friends, spinster sisters, whatever) to qualify for “marriage” too.