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 Indiana, the transmission of a sexually transmitted disease (STD) by an individual who knows or should have known about their infection to an uninformed partner can lead to both civil and criminal consequences. Under Indiana Code § 16-41-7-1, it is a Class B misdemeanor for a person who knows they have a communicable disease to fail to warn or take reasonable measures to prevent transmitting the disease to another person. This can escalate to a Class D felony if the disease transmitted is HIV/AIDS and the person knowingly or intentionally fails to warn their partner. Civil liability may also arise under negligence theories, where an infected person may be sued for damages for failing to inform their partner of their STD status before engaging in sexual activity. The duty to inform and prevent transmission is grounded in the responsibility to not harm others, and failure to adhere to this duty can result in legal repercussions.