A psychiatric hospital has a duty to warn a potential victim of the release of a patient, if it is aware or should have been aware that the patient threatened to harm that person. The failure to warn, however, does not automatically subject the hospital to liability, if any harm to the victim was caused by another person's unforeseeable negligence in dealing with the patient.

On March 1, 1990, Brenda Bishop petitioned to have her daughter, Tammi Lee Hartley, involuntarily committed to a psychiatric hospital. She had legal custody of Tammi's three-year-old daughter, Bobbi, and became alarmed when Tammi started making threats to injure Bobbi. Tammi was evaluated at Harris Psychiatric Hospital. On March 2, the hospital determined that Tammi was not mentally ill and released her.

The next day, Tammi went to her mother's house and after a visit, asked if she could take Bobbi out for a while. Despite the threats a few days before, Ms. Bishop agreed. When Bobbi was returned, however, she noticed that Bobbi had green lines from a magic marker all over her body, including her abdomen and vagina.

Ms. Bishop filed a negligence action against the South Carolina Department of Mental Health, alleging that the Department failed to warn of the mother's release, and failed to properly diagnose and treat the mother for her illness.

The trial court, however, granted summary judgment in favor of the Department holding that it owed no duty to warn of Tammi's release, and that the duty to properly diagnose and treat was owed only to the patient and not to a third party. The Court of Appeals affirmed on the same grounds.

The Supreme Court of South Carolina upheld the summary judgment, but on a different basis. The court found that the hospital did owe a duty to warn of the release of the mother, given its knowledge of her threats to injure her child. However, the grandmother's own unforeseeable negligence in allowing Tammi to take Bobbi from her home unsupervised was the proximate cause of the child's harm, particularly since, three days earlier, she had Tammi committed after threatening to harm Bobbi. Therefore the hospital was not responsible for Bobbi's harm, despite its failure to warn. The court also held that the hospital did not owe a duty to a third party regarding diagnosis and treatment.