In this article we deal with the responsibility and liability of the therapist for aggressive and criminal acts perpetuated by his psychiatric patient against third parties. This issue has been the object of controversial discussion among professionals in the legal and medical field since the famous case of Tarasoff (this psychiatric patient killed his former girlfriend after he informed his therapist of his intention to harm her. The therapist was sued because he did not warn nor protect the potential victim and did not prevent the criminal act). We describe the situation in the U.S. before Tarasoff and the implications of the decision of the Supreme Court of California in 1974-76 which dealt with this case and broadened the therapist's responsibility towards third parties. We also analyze the actual legal situation in Israel on this issue, its disadvantages and shortcomings. We suggest some proposals for improvement, together with some operational measures to cope with this complex issue including a thorough evaluation of the patient's clinical state, identification of the potential victim, warning and involvement of the relevant authorities, and hospitalization if needed.