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 Montana, 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 Montana law, specifically Montana Code Annotated (MCA) §45-5-207, the deliberate transmission of an STD may constitute a criminal offense. This statute makes it a crime to knowingly expose another person to an STD without their knowledge and consent. Civil liability may also arise under general tort principles such as negligence or battery, where an infected person may be sued for damages by the person who was infected. The infected individual could be held liable for failing to disclose their STD status before engaging in sexual activity, thereby causing harm to the other party. It is important for individuals to be aware of their health status and to communicate openly with sexual partners about any potential risks. An attorney can provide specific legal advice on these matters.