This study challenges the rationale for the criminalization of HIV transmission by demonstrating that prosecutions of these case are unlikely to serve the public health purpose of reducing HIV transmission from those who know they are living with HIV. The study analyzes information on criminal prosecutions for HIV exposure in the United States, including state and year, mode of exposure, type of law under which prosecution occurred, defendant and victim characteristics, and outcome. The authors found few prosecutions relative to HIV cases, and that prosecutions for spitting, biting, and prostitution were excessive when taking into account the risk of exposure; defendants’ behavior often involved no real exposure to HIV and, in the context of prostitution, convictions resulted even when the defendants had disclosed their HIV status beforehand. In the vast majority of cases, the law could have no deterrent effect due to the circumstances of the case; moreover there were many cases that raised serious concerns about whether deterrence was worth the cost to offenders. The article also raises the question of whether criminal laws could exert an influence on sexual behavior equivalent to that exerted by other social and personal factors, such as the desire for intimacy, the risk of violence from disclosure, and fears of discrimination.