Preventing HIV Transmission via HIV Exposure Laws: Applying Logic and Mathematical Modeling to Compare Statutory Approaches to Penalizing Undisclosed Exposure to HIV

Twenty-four U.S. states have enacted HIV exposure laws that prohibit HIV-positive persons from engaging in sexual activities with partners to whom they have not disclosed their HIV-status.1 From a public health perspective, HIV serostatus exposure laws can be viewed as structural interventions that seek to limit the spread of HIV by acting at the policy level.2 A central premise of these laws is that informed partners are more likely to protect themselves by declining sex, by substituting less risky activities for higher-risk ones, or by using condoms, than are uninformed partners. However, the effectiveness of these laws at preventing HIV transmission is not known.3 There is little standardization among existing HIV exposure laws, which vary substantially with respect to the sexual activities that are prohibited without prior serostatus disclosure.4 Among the strictest laws are those in Arkansas, Michigan, New Jersey, and Ohio which mandate disclosure prior to almost any type of sexual contact.3 Activities requiring prior serostatus disclosure include “sexual intercourse, cunnilingus, fellatio, anal intercourse, or any other intrusion, however slight, of any part of a person's body or of any object into the genital or anal openings of another person's body, but emission of semen is not required.”6 California's law is the least restrictive HIV exposure statute. The law criminalizes undisclosed exposure to HIV only when the HIV-positive person engages in unprotected anal or vaginal sex with an uninformed partner and does so intending to infect the partner.7 The California law offers HIV-positive persons a variety of choices for lawful sexual expression: they can either disclose their HIV status, use condoms during vaginal or anal intercourse, or engage in less risky sexual activities. The effectiveness of HIV exposure laws in reducing HIV transmission risk critically depends on the extent to which HIV-positive persons comply with these laws and the extent to which compliance with the law reduces HIV transmission risk. These two factors, in contrasting measure, are in turn dependent on the specific sexual activities that are prohibited, in the absence of disclosure, by a particular HIV exposure law. Compliance is likely to be greatest when statutes provide multiple options for lawful sexual expression with a partner, such as the following actions: engaging in alternatives to anal or vaginal intercourse, using condoms for vaginal or anal sex, or disclosing their positive serostatus to prospective sex partners and negotiating a level of risk that is acceptable to both partners. The more options individuals have, the easier it should be for them to comply with the law. Conversely, because condom use is not 100% effective8 and because oral sex is not entirely safe,9 less restrictive laws that permit condom-protected vaginal and anal intercourse and/or oral sex without disclosure might be less effective in preventing HIV transmission than stricter laws that prohibit these activities. No empirical data are available regarding the effectiveness of HIV serostatus exposure laws. It is not known whether, in fact, HIV exposure laws are effective at reducing HIV transmission risk, or whether stricter laws are more or less effective than more flexible laws. We developed a relatively simple analytic framework for evaluating the HIV prevention effectiveness of HIV exposure laws and applied this framework to two general classes of exposure laws: “strict” exposure laws that require serostatus disclosure prior to any sexual activity and more “flexible” laws that allow exemptions for condom-protected intercourse or other low-risk activities. We were particularly interested in identifying the following: (a) the circumstances in which each type of law would be more effective at reducing HIV transmission risk than the no-law alternative, and (b) determining the conditions under which flexible laws would be more effective than strict laws, and vice versa. Flexible laws always reduce transmission risk, and do so to a greater extent than do strict exposure laws when post-disclosure sex is riskier than low-risk sex.