In sickness and in health: same-sex marriage laws and sexually transmitted infections.

This paper analyzes the relationship between same-sex marriage laws and sexually transmitted infections in the United States using state-level data from 1981 to 2008. We hypothesize that same-sex marriage laws may directly affect risky homosexual behavior; may affect or mirror social attitudes toward gays, which in turn may affect homosexual behavior; and may affect or mirror attitudes toward non-marital sex, which may affect risky heterosexual behavior. Our findings may be summarized as follows. Laws banning same-sex marriage are unrelated to gonorrhea rates, which are a proxy for risky heterosexual behavior. They are more closely associated with syphilis rates, which are a proxy for risky homosexual behavior. However, these estimates are smaller and less statistically significant when we exclude California, the state with the largest gay population. Also, laws permitting same-sex marriage are unrelated to gonorrhea or syphilis, but variation in these laws is insufficient to yield precise estimates. In sum, the findings point to a modest positive association--if any at all--between same-sex marriage bans and syphilis.