How specific is the specificity rule in duty to warn or protect jurisprudence following the Pennsylvania Supreme Court's <i>Maas</i> decision?

Of the various rules establishing a mental health clinician's legal duty to take precautions to protect their patient from harming others, the most common is the specificity rule that limits the protective duty to warn reasonably identifiable victims. The specificity rule is important wherein the main or only specified protective measure is warning the victim. In the last quarter century, Pennsylvania adopted the specificity rule from its Supreme Court Emerich decision. In its recent Maas decision, the Pennsylvania Supreme Court expanded the duty to apply to potential victims who are unnamed and unidentifiable except for living on the same floor as the patient of a multiunit building. Victims constituted a group referenced by the patient as a "neighbor," but from the patient's threats both narrower "next door neighbor" and broader "anyone." We place this judicial expansion of the duty to warn within the context of professional ethics guidelines and state Tarasoff statutes that pertain to psychiatrists. The potential adverse consequences of this vague expansion of the specificity rule for clinicians, psychiatric patients, and unconnected citizens of Pennsylvania and for other jurisdictions in which courts could misguidedly follow this expansionist example are discussed, along with potential solutions.