Roderick Long (via Alas) writes about a case from 1886. Two "free-love activists," Lillian Harman and Edwin Walker, announced a marriage which they had performed in private — they didn't believe that either the state or the clergy were necessary.
The judge presiding over the case, Valentine, agreed that under common law “the mere living together as husband and wife of a man and woman competent to marry each other, with the honest intention of being husband and wife so long as they both shall live, will constitute them husband and wife, and create a valid marriage.” Still, he rejected the validity of the marriage:
In my opinion, the union between E. C. Walker and Lillian Harman was no marriage, and they deserve all the punishment which has been inflicted upon them. … In the present case, the parties repudiated nearly everything essential to a valid marriage, and openly avowed this repudiation at the commencement of their union.
(Quoted in Hal D. Sears, The Sex Radicals: Free Love in High Victorian America, p. 94.)
What "essentials" to a valid marriage had Walker and Harman "repudiated?" Long explains:
In their marriage ceremony Harman had declined not only to vow obedience to her husband (such a vow being repugnant both to her feminism and to her libertarian anarchism) but also to vow love unto death: “I make no promises that it may become impossible or immoral for me to fulfill, but retain the right to act, always, as my conscience and best judgment shall dictate.”
She also declined to submerge her individuality in another’s by taking her husband’s last name: “I retain, also, my full maiden name, as I am sure it is my duty to do.” Walker for his part vowed that “Lillian is and will continue to be as free to repulse any and all advances of mine as she has been heretofore. In joining with me in this love and labor union, she has not alienated a single natural right. She remains sovereign of herself, as I of myself, and we ... repudiate all powers legally conferred upon husbands and wives.”
In particular he repudiated any right as husband to control his wife’s property; he also acknowledged his “responsibility to her as regards the care of offspring, if any, and her paramount right to the custody thereof should any unfortunate fate dissolve this union.” Harman’s father added: “I do not ‘give away the bride,’ as I wish her to be always the owner of her person.” (Sears, p. 85.)
Thus, according to Judge Valentine, the "essentials" of marriage included: life-long commitment, a wife's obedience to the husband, the husband's absolute control over all property, the wife taking the husband's last name, the right of the husband to force sexual intercourse on an unwilling wife (that would be rape, by the way), and the right of the husband to control and have custody of any children.
Long also quotes Horace "go west, young man" Greeley from an 1853 debate over free love:
[T]his reminds me of the kindred case of two persons in Nantucket who have advertised in the newspapers that they have formed a matrimonial connection for life, or as long as they can agree; adding, that they consider this partnership exclusively their own affair, in which nobody else has any concern. I am glad they have the grace not to make the State a party to any such arrangement as this. But true Marriage – the union of one man with one woman for life, in holy obedience to the law and purpose of God, and for the rearing up of pure, virtuous, and modest sons and daughters to the State – is a union so radically different from this, that I trust the Nantucket couple will not claim, or that, at all events, their neighbors will not concede, to their selfish, shameful alliance the honorable appellation of Marriage. Let us, at least, “hold fast the form of sound words.”
This is consistent with Valentine's ruling and Long argues that if today's opponents of same-sex marriage also want to “hold fast the form of sound words” and thereby maintain a traditional understanding of marriage, then they should reject the legitimacy of current unions which do not "require the wife’s legal subordination to her husband, or fail to require her to take her husband’s last name, or do not give the husband total control over his wife’s body, property, and children..."
I wonder, alongside Long, how opponents of same-sex marriage can argue that their definition of marriage is preferable to the definition used by Greeley and Valentine, given the fact that the "selling point" of their definition is that it is allegedly "traditional." Of course, this question assumes that opponents of same-sex marriage don't reject the definition used by Greeley and Valentine — but I'm not sure that that's the case. They may not say much openly to promote it, but as we saw in the recent revelations of Dr. W. David Hager, there is much in their behavior that is consistent with how Greeley and Valentine saw marriage.