Knowingly Transmitting an Infectious Disease – Health & Safety Code 120290 HS
Infectious diseases can spread quickly—but when a disease is intentionally transmitted, California law treats that conduct as a crime.
Under California Health & Safety Code § 120290, it is illegal to knowingly transmit or deliberately expose another person to an infectious or communicable disease.
This statute is commonly referred to as California's “willful exposure” law.
Although it is most often associated with the intentional transmission of sexually transmitted diseases (STDs), such as HIV or herpes, the law has also been applied to the deliberate spread of diseases like COVID-19.
If you are accused of violating HS 120290, you could face criminal charges, jail time, and fines, making early legal representation critical.
What Does Health & Safety Code 120290 Prohibit?
Health & Safety Code 120290 criminalizes two distinct types of conduct involving infectious diseases:
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Intentional transmission of an infectious or communicable disease
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Willful exposure to an infectious or communicable disease
Both offenses require proof of specific legal elements and are treated as misdemeanor crimes under California law.
What Is an “Infectious or Communicable Disease”?
An infectious or communicable disease is defined as:
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A disease that spreads from person to person
Either directly or indirectly. -
A disease with significant public health implications
Meaning it poses a serious risk to the community.
Common examples include:
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HIV and AIDS
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Herpes, gonorrhea, and chlamydia
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Other serious sexually transmitted infections
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COVID-19 and similar highly contagious illnesses
Minor illnesses, such as the common cold, generally do not qualify unless special circumstances create a serious health risk.
Intentional Transmission of an Infectious Disease
To convict someone of intentional transmission, prosecutors must prove all of the following beyond a reasonable doubt:
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You knew you were infected with an infectious or communicable disease
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You acted with the specific intent to transmit the disease
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You engaged in conduct posing a substantial risk of transmission
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The other person contracted the disease
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The other person did not know you were infected and voluntarily participated
If the prosecution fails to prove even one of these elements, the charge may fail.
Willful Exposure to an Infectious Disease
Willful exposure is a separate offense under HS 120290. It occurs when:
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A qualified health professional instructs you not to engage in conduct that poses a substantial risk of transmission
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You violate those instructions within 96 hours
This typically arises when a person is advised to isolate or take precautions but knowingly disregards medical instructions and exposes others.
Conduct That Poses a “Substantial Risk of Transmission”
Conduct that poses a substantial risk is any behavior that current medical science recognizes as having a reasonable probability of transmitting the disease.
Examples include:
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Unprotected sexual activity
When infected with an STD. -
Sharing hypodermic needles
For drug use or medical purposes. -
Deliberately coughing or breathing on others
When infected with COVID-19 or another airborne illness.
Third-Party Exposure Liability
HS 120290 also applies to third-party conduct. A person can be charged even if they are not infected themselves.
You may be liable if:
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You know a third party is infected
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You intentionally encourage or facilitate risky exposure
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The victim becomes infected as a result
In such cases, the law treats the conduct as if you personally transmitted the disease.
Examples of Health & Safety Code 120290 Violations
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Engaging in unprotected sex without disclosing an STD
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Sharing needles without revealing HIV-positive status
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Deliberately attempting to infect someone with COVID-19
Penalties for Violating HS 120290
Violations of Health & Safety Code 120290 are misdemeanor offenses.
If convicted, you may face:
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Up to one year in county jail
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A fine of up to $1,000
Although the charge is not a felony, the consequences can still be serious and long-lasting.
Additional Penalty Enhancements for Sex Crimes
Under Penal Code § 12022.85, an additional three-year sentencing enhancement applies to certain sex crimes committed by persons with HIV or AIDS.
This enhancement applies to:
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Rape (Penal Code § 261)
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Statutory rape (Penal Code § 261.5)
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Sodomy (Penal Code § 286)
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Oral copulation (Penal Code § 287)
These enhancements can significantly increase sentencing exposure.
Common Defenses to HS 120290 Charges
A skilled California criminal defense attorney may raise several defenses, depending on the facts of the case.
Common defenses include:
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Lack of knowledge of infection
You cannot intentionally transmit a disease you did not know you had. -
Lack of intent to transmit
Using practical prevention measures, such as condoms or masks, may negate intent. -
No transmission occurred
If the other person was not infected, intentional transmission cannot be proven. -
Causation issues
The infection may have come from another source. -
Informed consent
If the other person knew of the infection and voluntarily participated, the charge may fail.
Speak With a California Criminal Defense Attorney
Allegations of knowingly transmitting an infectious disease can have serious legal, personal, and reputational consequences. Early legal intervention can make a critical difference in how your case is resolved.
The Los Angeles-based criminal defense law firm of Cron, Israels & Stark represents individuals accused of violating Health & Safety Code § 120290 and related offenses.
Contact our office at 424-372-3112 to review your legal options and protect your rights.