The third requirement to succeed in a medical malpractice lawsuit is causation. A doctor's action caused the patient's harm if, but for that action, the patient would not have been harmed. The proximate cause inquiry asks whether, if the action did in fact cause the harm, the professional ought to be held responsible for his or her actions. In some rare instances, the physician's actions are so removed from the final harm to the patient that the law cuts off liability for those actions by saying that the tortious conduct was not proximate to the harm. In other words, there is not a close enough connection between the action and the harm to say there is proximate causation.
Thorny issues arise when the harm to the patient had more than one cause.
For example, two doctors, acting independently, might both prescribe the same wrong medication. The Ohio Legislature has recently enacted laws which impact this issue in medical malpractice cases . A physician or hospital has both an ethical and legal duty to preserve in confidence any communication from his patient unless the patient instructs otherwise. Generally, a doctor violates a patient's right to confidentiality by releasing information about his or her medical condition to unauthorized persons or organizations without first having obtained the written consent of the patient. In order to obtain more than nominal damages in a case of a breach of confidentiality, a person must show that the doctor's careless disclosure caused him or her great harm.