The transmission of a sexually transmitted disease (STD) from a person who knows or should know they have the disease to another person who is not informed of that fact before engaging in sexual contact with the infected person may result in both civil liability (for money damages) and criminal liability (for penalties).

Laws vary from state to state and some states have both civil and criminal statutes (laws enacted by the state legislature) that specifically address the transmission of sexually transmitted diseases. In other states civil lawsuits may be filed and criminal prosecutions may be made under traditional legal theories such as negligence in a civil lawsuit and battery (harmful or offensive physical contact without consent) in a criminal prosecution.

In California, the willful exposure to an STD can lead to both civil and criminal consequences. Civilly, an individual who knowingly transmits an STD to an uninformed partner may be sued for negligence or battery, potentially resulting in monetary damages. California Civil Code Section 1714.01 specifically addresses the civil liability for the knowing transmission of an STD, including HIV. On the criminal side, California Health and Safety Code Section 120290 makes it a misdemeanor or felony to willfully expose another to an STD, including HIV, with the intent to infect them. The severity of the criminal charge can depend on factors such as the intent to harm and the specific STD transmitted. It is important for individuals to be aware of these laws and to disclose their STD status to potential sexual partners. An attorney can provide more detailed information on the potential legal consequences of transmitting an STD in California.