In most U.S. states, yes, failing to disclose a known STD to a sexual partner can be illegal, but the specifics vary dramatically depending on which infection you have, which state you live in, and whether transmission actually occurred. HIV has the most extensive legal framework, with roughly 35 states maintaining some form of criminalization for non-disclosure. For other STDs like herpes, syphilis, or gonorrhea, criminal statutes are less common, but you can still face serious civil liability in nearly every state.
Criminal Laws for HIV Non-Disclosure
HIV non-disclosure carries the most severe criminal consequences. Many states treat knowingly exposing someone to HIV without disclosing your status as a felony, regardless of whether transmission actually occurs. In South Carolina, for example, knowingly exposing another person to HIV through sexual intercourse is a felony punishable by up to ten years in prison and a $5,000 fine. Other states have similar statutes with penalties ranging from misdemeanor charges to multi-year felony sentences.
The key element in most of these laws is knowledge. If you’ve been diagnosed with HIV and have sex with someone without telling them, prosecutors can charge you even if your partner never contracts the virus. The crime is the exposure itself, not necessarily the result.
Since 2014, at least nine states (California, Colorado, Illinois, Iowa, Michigan, Missouri, Nevada, North Carolina, and Virginia) have modernized or repealed their HIV criminal laws to better reflect current medical science. These updates have taken different forms: some states now require prosecutors to prove actual intent to transmit rather than just non-disclosure, others have added legal defenses for people who take steps to prevent transmission, such as maintaining viral suppression, using condoms, or having a partner on preventive medication.
How Undetectable Viral Load Changes the Picture
Medical science has established that a person living with HIV who maintains an undetectable viral load cannot sexually transmit the virus. This principle, known as U=U (undetectable equals untransmittable), is increasingly shaping the legal landscape. In Michigan, for instance, the law does not require you to disclose your HIV status if you maintain an undetectable viral load and do not have intent to transmit.
Not all states have caught up. In jurisdictions that haven’t modernized their statutes, you may still face criminal charges for non-disclosure even if your viral load makes transmission effectively impossible. This is one of the most contested areas in public health law right now, as older statutes were written before effective treatment existed.
Criminal Laws for Other STDs
For infections like herpes, gonorrhea, syphilis, chlamydia, and HPV, the criminal landscape is thinner. Some states have general statutes that criminalize knowingly transmitting any communicable or sexually transmitted disease. South Carolina’s law, for example, makes violating its STD control provisions a misdemeanor punishable by up to $200 in fines or 30 days in jail. Other states have similar broad statutes, though enforcement is uncommon for non-HIV infections.
There is no universal federal law requiring disclosure of any STD. The responsibility for STI reporting and partner notification lies entirely with individual states. The CDC has noted that bacterial STI diagnoses do not automatically trigger any legal requirement because these infections do not typically represent an imminent danger of serious bodily harm in the way courts have historically defined it.
Civil Lawsuits Are the Bigger Risk
Even where criminal charges are unlikely, the person you exposed can sue you. Civil lawsuits for STD transmission are filed regularly and can result in significant financial damages. Courts recognize several legal theories that give your partner grounds to take you to court.
Negligence: Your partner can argue that you knew or should have known you were infected, that you had a duty to disclose that information, and that your failure to do so caused them harm. The central idea is that you owed your partner enough information to make their own decision about the risk. In some states, liability exists even if transmission didn’t actually occur, because the exposure itself constitutes a breach of duty.
Battery: While your partner may have consented to sex, they did not consent to contact that carried the known risk of contracting an STD. Courts have held that proceeding with sexual contact while knowing you could transmit an infection is enough to establish battery. You don’t need to have intended to infect them; knowing that transmission was possible and going forward anyway is sufficient.
Fraud: If you actively concealed your diagnosis or lied about your status with the intention of having sex, your partner can bring a fraud claim. This requires proving that you knew about your infection and deliberately hid it.
Intentional infliction of emotional distress: Contracting an STD from someone who hid their status causes real psychological harm, including anxiety, depression, and humiliation. Courts allow claims for emotional distress damages, though these are typically filed alongside negligence or battery claims because proving emotional distress on its own is difficult.
What About Your Doctor’s Role?
Your doctor is required to report your STD diagnosis to the state or local health department. That’s a public health obligation, not a disclosure to your partners. Despite a common assumption that doctors must warn your sexual contacts, the CDC has found that very few states have laws requiring healthcare providers to directly notify a patient’s sex partners about common bacterial STDs.
In California, physicians are expected to work with the patient to bring partners in for examination. If there’s no evidence the partner received treatment within 10 days, the physician reports the suspected case to the health department. In most other states, the provider’s duty stops at reporting to public health authorities, and the health department decides whether to conduct partner notification.
The practical result is that partner notification often depends on voluntary cooperation from the diagnosed person. Health departments may reach out to named contacts, but there is no nationwide system guaranteeing your partners will be informed.
How Other Countries Handle Disclosure
Canada takes a particularly strict approach. The Supreme Court of Canada ruled in 2012 that a person has a legal duty to disclose their HIV-positive status before any sexual activity that poses a “realistic possibility of transmission.” Non-disclosure has been prosecuted under aggravated sexual assault and aggravated assault charges, even though Canada’s Criminal Code doesn’t contain HIV-specific offenses. However, Canadian courts have also recognized that there is no realistic possibility of transmission when someone has a suppressed viral load (under 200 copies per milliliter of blood) and uses a condom, meaning the criminal law should not apply in those circumstances.
Canada’s Department of Justice has further clarified that criminal prosecution should generally not apply to people on treatment, people who use condoms, or people who engage only in oral sex, unless additional risk factors are present. Criminal law is reserved for cases involving high-risk conduct where public health interventions have failed.
What This Means Practically
The legal risk of not disclosing an STD is real and comes from multiple directions. Criminal prosecution is most likely with HIV in states that haven’t modernized their laws. Civil lawsuits are possible with any STD in any state, and they don’t require proof that you intended harm or even that transmission occurred. The common thread across criminal and civil liability is knowledge: once you know or have reason to believe you’re infected, you have a legal and ethical duty to tell your partners before sexual contact so they can make an informed choice.