The Volokh Conspiracy
Mostly law professors | Sometimes contrarian | Often libertarian | Always independent
Some readers have asked: Once same-sex marriages are legalized—whether by a Supreme Court decision or just by state law—would extramarital sex by a partner to such a marriage be adultery? This may be relevant in the very few jurisdictions where adultery is still prosecuted (the military justice system is the one I know of), but also if the parties' adultery is relevant to a divorce (for instance, in states which require that the spouses lived apart for some months before a divorce is granted, but not when adultery is shown) or to whether alimony is granted.
Yes—and no. The adultery laws that I've seen generally define adultery without regard to the sex of the parties (rejecting the historical rule that a married woman had to be involved). So that would apply to same-sex marriages, especially if the Court holds that the Equal Protection Clause bars discrimination against same-sex marriages.
But many adultery statutes define adultery as involving "sexual intercourse," and some states define "sexual intercourse" as limited to genital sex. Consider, for instance, In re Blanchflower (N.H. 2003):
The [husband] filed for divorce from the [wife] on grounds of irreconcilable differences. He subsequently moved to amend the petition to assert the fault ground of adultery under RSA 458:7, II. Specifically, the [husband] alleged that the [wife] has been involved in a "continuing adulterous affair" with the [lover], a woman, resulting in the irremediable breakdown of the parties' marriage….
RSA 458:7 provides, in part: "A divorce from the bonds of matrimony shall be decreed in favor of the innocent party for any of the following causes: … II. Adultery of either party." The statute does not define adultery….
The plain and ordinary meaning of adultery is "voluntary sexual intercourse between a married man and someone other than his wife or between a married woman and someone other than her husband." Webster's Third New International Dictionary 30 (unabridged ed. 1961). Although the definition does not specifically state that the "someone" with whom one commits adultery must be of the opposite gender, it does require sexual intercourse.
The plain and ordinary meaning of sexual intercourse is "sexual connection esp. between humans: COITUS, COPULATION." Webster's Third New International Dictionary 2082. Coitus is defined to require "insertion of the penis in the vagina," Webster's Third New International Dictionary 441, which clearly can only take place between persons of the opposite gender.
We also note that "[a] law means what it meant to its framers and its mere repassage does not alter that meaning." The statutory compilation in which the provision now codified as RSA 458:7 first appeared is the Revised Statutes of 1842…. Our cases from that approximate time period … support the inference that adultery meant intercourse.
Cases from this period also indicate that adultery as a ground for divorce was equated with the crime of adultery and was alleged as such in libels for divorce. Although the criminal adultery statute in the 1842 compilation also did not define adultery, roughly contemporaneous case law is instructive: "Adultery is committed whenever there is an intercourse from which spurious issue may arise …." As "spurious issue" can only arise from intercourse between a man and a woman, criminal adultery could only be committed with a person of the opposite gender. [Note that treating this as applying to married woman-single man sex but not single woman-married man sex would likely violate the modern Equal Protection Clause caselaw. -EV]
We note that the current criminal adultery statute still requires sexual intercourse ….
We reject the [husband]'s argument that an interpretation of adultery that excludes homosexual conduct subjects homosexuals and heterosexuals to unequal treatment, "contrary to New Hampshire's public policy of equality and prohibition of discrimination based on sex and sexual orientation." Homosexuals and heterosexuals engaging in the same acts are treated the same because our interpretation of the term "adultery" excludes all non-coital sex acts, whether between persons of the same or opposite gender. The only distinction is that persons of the same gender cannot, by definition, engage in the one act that constitutes adultery under the statute.
The [husband] also argues that "[p]ublic policy would be well served by applying the same law to a cheating spouse, whether the promiscuous spouse chooses a paramour of the same sex or the opposite sex." This argument is tied to the premise, as argued by the [husband], that "[t]he purpose underlying [the adultery] fault ground is based upon the fundamental concept of marital loyalty and public policy's disfavor of one spouse's violation of the marriage contract with another."
We have not, however, seen any such purpose expressed by the legislature. As noted above, the concept of adultery was premised upon a specific act. To include in that concept other acts of a sexual nature, whether between heterosexuals or homosexuals, would change beyond recognition this well-established ground for divorce and likely lead to countless new marital cases alleging adultery, for strategic purposes. In any event, "it is not the function of the judiciary to provide for present needs by an extension of past legislation." Similarly, "we will not undertake the extraordinary step of creating legislation where none exists. Rather, matters of public policy are reserved for the legislature."
The dissent defines adultery not as a specific act of intercourse, but as "extramarital intimate sexual activity with another." This standard would permit a hundred different judges and masters to decide just what individual acts are so sexually intimate as to meet the definition….
For a similar definition of "sexual intercourse" (though outside the context of deciding whether an act constituted adultery), see Commonwealth v. Smith (Mass. 2000). For a definition of adultery that extends to nongenital sex—the more sensible view, I think, so long as it's not precluded by state law—see Patin v. Patin, 371 So.2d 682, 683 (Fla. Dist. Ct. App.1979); Owens v. Owens, 274 S.E.2d 484, 485-86 (Ga. 1981); S.B. v. S.J.B., 609 A.2d 124 (N.J. trial ct. 1992); RGM v. DEM, 410 S.E.2d 564, 566-67 (S.C. 1991)
Now of course this narrow definition of adultery isn't limited to same-sex marriages as such. It means that heterosexual oral or anal sex wouldn't count as adultery—and it means that genital sex outside a same-sex marriage does count as adultery: If Wanda and Wendy are married, but Wendy then has genital sex with Larry, that is adultery. But it does mean that what is likely the typical cheating by a same-sex spouse will not count as adultery in those states that adopt this narrow definition.
Of course, if the Supreme Court holds that it's unconstitutional to treat same-sex marriage differently from opposite-sex marriage, one could argue that it's likewise unconstitutional to treat sexual conduct that is characteristic of same-sex relationships differently from sexual conduct that can only take place in opposite-sex relationships. Much would depend on the particular reasoning of the Court decision (or of state court decisions recognizing same-sex marriage rights, if you are in a state in which a court had so decided). And, especially when there's no state statute expressly limiting adultery to genital sex, one can argue that changing social attitudes—not just to homosexuality, but to nongenital sex more broadly, which has made nongenital sex much more common even among opposite-sex couples—should lead to a broader reading of "sexual intercourse." (This sort of changing attitudes argument might be especially apt as to civil cases, and less so as to the rare criminal adultery cases.)
But in at least some states, it is at least possible—indeed, perhaps likely—that nongenital extramarital sex, whether the marriage is same-sex or opposite-sex, and whether the cheating is same-sex or opposite-sex, does not constitute adultery.