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 Colorado, 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 Colorado law, civil liability may arise if the infected person's actions are deemed negligent, meaning they failed to take reasonable care to prevent the transmission of the STD. This could result in a lawsuit for monetary damages. On the criminal side, Colorado Revised Statutes § 18-3-415 addresses the criminal transmission of an STD. It is a crime for a person who knows they are infected with HIV to engage in sexual activity without disclosing this information to their partner. Penalties for such criminal offenses can include fines and imprisonment. It's important to note that while HIV is specifically mentioned in the criminal statute, other STDs may still be subject to prosecution under general criminal laws such as assault or battery. An attorney can provide guidance on the specifics of these laws and their application in individual cases.