Physicians play a critical role in preventing and treating firearm injury, although the scope of that role remains contentious and lacks systematic definition. This piece aims to utilize the fundamental principles of medical ethics to present a framework for physician involvement in firearm violence. Physicians' agency relationship with their patients creates ethical obligations grounded on three principles of medical ethics - patient autonomy, beneficence, and nonmaleficence. Taken together, they suggest that physicians ought to engage in clinical screening and treatment related to firearm violence. The principle of beneficence also applies more generally, but more weakly, to relations between physicians and society, creating nonobligatory moral ideals. Balanced against physicians' primary obligations to patient agency relationships, general beneficence suggests that physicians may engage in public advocacy to address gun violence, although they are not ethically obligated to do so. A fourth foundational principle - justice - requires that clinicians attempt to ensure that the benefits and burdens of healthcare are distributed fairly.