Sometimes physicians assume responsibilities to third parties when undertaking the care of patients. Physicians have been held liable to third parties, though strangers to the patients, for failing to warn regarding the communicability of contagious diseases. Two suits have been allowed against physicians by third parties who were injured by drivers of vehicles who had not been warned by the physician of the danger of driving caused by their medical problem. Hospitals and psychiatrists have been held liable to injured third parties for failing to warn of the dangerous propensities of their patients under psychotherapy. Courts have held that such disclosures do not violate the patient's right to privacy and confidentiality. However, physicians may exercise professional discretion and need not warn if, in their judgment, that would be unreasonable, unnecessary, or harmful. Nevertheless, rights of patients must yield to the public interest when it collides with public safety and welfare.