Final answer:
The duty to warn regulation for psychologists came from the Tarasoff vs. Regents of the University of California case, establishing the responsibility to protect potential victims from harm.
Step-by-step explanation:
The ethical duty to warn regulation that requires psychologists to report when a client may hurt another person arose after the famous court case Tarasoff vs. Regents of the University of California. This landmark decision was established in 1976 and mandates that mental health professionals must break confidentiality when their patients present a serious danger to others, in essence, they have the predictive possibility and ethical obligation to warn potential victims.
This ruling emphasizes the psychologist's duty to protect individuals who are being threatened by a client's serious predictions of harm, a concept that balances clinical judgment and the protection of potential victims against the importance traditionally placed on client confidentiality.