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Duty to Warn and Tarasoff: The Case, the Rule and How States Differ
The duty to warn comes from Tarasoff v. Regents of the University of California. In 1974 the California Supreme Court held that a therapist who determines a warning is essential to avert danger must give it. On rehearing in 1976 it replaced that with a broader rule: a therapist who determines a patient poses a serious danger of violence “bears a duty to exercise reasonable care to protect the foreseeable victim”, by warning them, the police or taking other reasonable steps (the 1976 opinion). Whether that duty is mandatory, only permitted or not imposed at all depends on the state (NCSL).
For the wider rules on what clinicians can share and when, see patient confidentiality. This page goes deep on the duty to warn, with sources read October 31, 2026. It is an orientation, not legal advice.
The Tarasoff case: what happened
As alleged in the complaint the court reviewed, which was brought by Tatiana's parents (17 Cal.3d 425):
- Two months before the killing, Prosenjit Poddar told Dr. Lawrence Moore, a psychologist at the Cowell Memorial Hospital at UC Berkeley, that he intended to kill Tatiana Tarasoff.
- At Moore's request campus police briefly detained Poddar, but released him when he appeared rational.
- Moore's superior then directed that no further action be taken to detain him.
- No one warned Tatiana or her family. On October 27, 1969, Poddar killed her.
What the court held: from a duty to warn to a duty to protect
The court ruled twice. Its 1974 decision, often called Tarasoff I (529 P.2d 553), said a therapist who determines, or should determine, that a warning is essential to avert danger “incurs a legal obligation to give that warning.” The court then reheard the case and revised its decision in 1976, Tarasoff II (Journal of the American Academy of Psychiatry and the Law).
The court said the public policy protecting therapist-patient confidentiality “must yield to the extent to which disclosure is essential to avert danger to others,” adding: “The protective privilege ends where the public peril begins.” The duty it described is a duty to protect. The court said meeting it may call for warning the intended victim or others likely to tell her, notifying the police, or taking whatever other steps are reasonably necessary (the opinion). Warning is one way, not the only one.
How states differ on the duty to warn
NCSL says Tarasoff led to duty to warn or duty to protect laws in almost every state, and that most states either require or permit mental health professionals to disclose information about patients who may become violent. Its state chart, last updated March 16, 2022, shows how much the rules differ (NCSL):
| Type of rule | Examples | What it means |
|---|---|---|
| Mandatory | Examples: California, Maryland, New York, Ohio | What it means: The professional must act when the conditions are met. New York requires a report to state government when a patient presents a serious and imminent danger. |
| Permissive | Examples: Texas, Florida | What it means: The professional may disclose but is not required to. Texas allows disclosure only to medical or law enforcement personnel. |
| Duty to protect, not warn | Examples: Georgia | What it means: No duty to warn, but case law creates a duty to protect identifiable third parties in some situations. |
| No duty | Examples: Maine | What it means: No duty to warn or protect, and confidentiality is enforced. |
NCSL lists California, where Tarasoff was decided, as mandatory, with the note that the statute is permissive but case law interprets it as mandatory. The American Psychological Association has argued for leaving room for professional judgment (NCSL).
How HIPAA and the AMA Code fit
HIPAA permits a disclosure that is necessary to prevent or lessen a serious and imminent threat to the health or safety of a person or the public, made to someone reasonably able to prevent it, including the target (45 CFR 164.512). HHS says that can include family, friends, caregivers and law enforcement, and that HIPAA defers to the professional judgment of health professionals (HHS).
For physicians, the AMA Code allows disclosure without consent to third parties who can mitigate the threat when there is a reasonable probability that the patient will seriously harm themselves or an identifiable person, and asks that it be limited to the minimum necessary (AMA Code).
If a patient makes a threat: a step-by-step
Our steps for a clinical setting or an interview scenario:
- Take it seriously and get specifics. Who is the target, how and when, and does the patient have the means?
- Get help now. As a student or trainee, tell your supervising clinician right away. Do not decide alone.
- Know the threshold. A serious threat to an identifiable person is different from venting anger.
- Share the minimum necessary. With the person who can prevent the harm: the target, the police, or both, as the law and the team decide.
- Document and follow up. What was said, what was done and why, and the plan for the patient's care.
Practice question: a threat while you are shadowing
Why interviewers like this scenario
It tests whether you know confidentiality has limits, whether you stay inside your role, and whether you act fast without acting alone. The strongest answers do all three in under two minutes.
“You are shadowing in a clinic. A patient tells you, while the doctor is out of the room, that he is going to make his ex-girlfriend pay and that he knows where she works. What do you do?”
A duty to warn station. A strong answer takes the threat seriously, gets the supervising physician involved immediately, and understands that confidentiality has limits without acting alone.
Example answer written by Confetto (the applicant is invented)
I would take what he said seriously and stay calm with him. I would not promise to keep it between us, and I would not argue with him. I might ask what he means, because whether this is anger or a specific plan matters a great deal.
Then I would tell the physician as soon as he or she is back, or step out and find them right away if it sounds urgent. As a shadowing student I have no role in deciding what happens next, but I do have a responsibility to make sure the person who does knows.
Confidentiality matters, and patients need to trust that what they say stays private. But it has limits. When a patient seriously threatens an identifiable person, the physician may need to warn her or the police, and depending on the state, the law may require it. The doctor will know the rules and the clinic's policy.
I would also stay aware of my own safety and everyone else's in the clinic, and afterward I would write down exactly what he said so the physician has an accurate account.
Sources: the 1976 Tarasoff opinion (Stanford SCOCAL), the Journal of the American Academy of Psychiatry and the Law on the 1974 decision, NCSL's duty to warn chart, 45 CFR 164.512, HHS and the AMA Code of Medical Ethics, checked October 31, 2026.
Frequently asked questions
What was the Tarasoff case?
In 1969 Prosenjit Poddar killed Tatiana Tarasoff, two months after, her parents alleged, telling a university psychologist he intended to. The California Supreme Court first ruled in 1974 that a therapist must give a warning when one is essential to avert danger, then reheard the case and in 1976 held that a therapist must use reasonable care to protect the foreseeable victim. Read the 1976 opinion.
What is the difference between duty to warn and duty to protect?
Duty to warn means telling the intended victim, which is what the 1974 Tarasoff decision required. The 1976 decision framed a broader duty to protect, which the court said might be met by warning the victim or others, notifying the police, or other reasonable steps.
Is the duty to warn the same in every state?
No. NCSL's chart shows states where the duty is mandatory, states where disclosure is only permitted, and states with no duty. Check the law where you practice. See NCSL's state chart.
Does HIPAA allow a duty to warn disclosure?
Yes. HIPAA permits disclosure to prevent or lessen a serious and imminent threat to a person or the public, to someone reasonably able to prevent it, including the target. HHS says it defers to the professional judgment of health professionals. See 45 CFR 164.512.
Does the duty to warn apply to physicians, or only therapists?
Most state duty to warn laws are written for mental health professionals. For physicians, the AMA Code allows disclosure to third parties who can mitigate a threat when there is a reasonable probability of serious harm to an identifiable person. Read the AMA opinion.