Transmitting an STD in Montana

In Montana, it is a misdemeanor for anyone who knows that he or she is infected with HIV or another sexually transmitted disease (STD) to expose another person to the disease.

In Montana, it is a misdemeanor for anyone who knows that he or she is infected with HIV or another sexually transmitted disease (STD) to expose another person to the disease.

For more information on the criminal transmission of STDs, see Transmitting an STD: Criminal Laws & Penalties.

Sexually Transmitted Diseases

Under Montana’s laws, STDs include:

  • human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS), and
  • the bacterial infections syphilis, gonorrhea, chlamydia, chancroid, lymphogranuloma venereum, and granuloma inguinale.

(Mont. Code Ann. § 50-18-101.)

Exposing Another to an STD

In Montana, it is a crime for people who know that they are infected with a sexually transmitted disease to expose another person to infection.

(Mont. Code Ann. §§ 45-2-101, 50-18-112.)

Although Montana’s laws do not provide a list of prohibited activity, exposure to sexually transmitted diseases is most likely to occur through sexual contact, particularly unprotected sexual contact, and needle sharing.

Intentional, knowing, or negligent exposure

In order to be convicted of criminal exposure, the defendant must act intentionally, knowingly, or negligently. People act intentionally when they act with a particular purpose. For example, someone who engages in unprotected sexual contact to deliberately expose a partner to HIV has acted intentionally.

Many criminal prosecutions are based on the theory that a defendant knowingly or negligently exposed another to an STD. People act knowingly when they are aware of a high probability that exposure will result from their conduct and negligently when they consciously disregard the risk of exposure. Negligent behavior is always a gross deviation from how a reasonable person would act.

(Mont. Code Ann. §§ 45-2-101, 45-2-103.)


Having unprotected sex with another person while you are currently infected with gonorrhea would probably be considered knowingly exposing another. Evidence that a defendant had been tested for HIV or syphilis, and then failed to follow up on the test results, despite the fact that someone from the clinic had called several times and sent letters to defendant indicating that the clinic had very important news to give defendant, might establish negligence.


Under Montana’s s laws, people who do not know that they are infected are not guilty of a crime.

In some states, it is a defense if the defendant tells the victim of the infection and obtains the victim’s consent to exposure, but Montana’s laws do not allow for this defense.


Exposing another person to a sexually transmitted disease is a misdemeanor, punishable by up to six months in jail and a fine of up to $500.

(Mont. Code Ann. §§ 46-18-212, 50-18-113.)

Getting Legal Advice and Representation

Being convicted of exposing another to an STD can result in time in jail and a fine. If you are charged with this crime, you should contact a Montana criminal defense attorney as soon as possible. An attorney will be able to tell you how your case is likely to be treated in court, depending on the judge and prosecutor assigned to your case and the facts. With an attorney’s help, you can obtain the best outcome in your case.

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