On-call physicians encounter a diverse aggregate of interfaces with sundry persons concerning patient care that may surface potential legal peril. The duties and obligations of an on-call physician, who must act as a fiduciary to all patients, create a myriad of circumstances where there is a risk of falling prey to legal ambiguities. The understanding of the doctor–patient relationship, the obligations of physicians under the Emergency Medical Treatment and Labor Act, the meaning of medical informed consent and the elements of negligence will help physicians avoid the legal risk associated with the various encounters of being on call. After introducing the legal concepts, we will explore the interactions that may put physicians at legal risk and outline how to mitigate that risk. Being on call is time consuming and arduous. While on call, physicians have a duty to act morally and ethically in the best interest of the patients.