In many states it is a criminal offense to intentionally or recklessly transmit a sexually transmitted disease (STD or venereal disease) to another person. Examples of such diseases include HIV/AIDS, syphilis, gonorrhea, chlamydia, genital herpes, human papillomavirus (HPV), genital warts, and hepatitis B.

Laws vary from state to state, and in some states these laws include other infectious or communicable diseases. In some states there is a specific criminal offense for transmission of sexually transmitted or communicable diseases, and in other states criminal prosecutors charge the defendant with a more general crime like assault.

Laws regarding criminal liability for the intentional or reckless transmission of sexual or other infectious or communicable diseases are generally located in a state’s statutes—often in the penal or criminal code, or the health and safety code.

A person who negligently transmits a sexually transmitted disease to another person through sexual contact—without informing the other person of the offender’s infection before the sexual contact—may also be subject to civil liability for money damages in a lawsuit.

In Missouri, it is a criminal offense to knowingly expose another person to HIV without their consent. Missouri law, specifically under Missouri Revised Statutes Section 191.677, makes it a felony for an individual who is aware that they are infected with HIV to act in a reckless manner by exposing another person to the virus through sexual intercourse or other activities that could result in the transmission of HIV without the knowledge and consent of the other person. This law has been subject to criticism and calls for reform, as it does not take into account the actual risk of transmission, especially in the context of modern treatments that can make the virus undetectable and non-transmissible. Additionally, for other STDs like syphilis, gonorrhea, chlamydia, and hepatitis B, Missouri's laws may address the transmission under broader statutes related to assault or reckless endangerment, depending on the circumstances of the transmission. Civil liability may also arise if someone negligently transmits an STD to another person, potentially resulting in a lawsuit for monetary damages.