Right to practice medicine regulated by statute.--In the absence of a statute upon the subject, any person is at liberty to practice medicine or surgery or both. This is the common law. And yet in the absence of a statute the physician necessarily assumes certain responsibilities that grow out of his relation to those whom he treats. He is bound to bring to the discharge of his duties the learning, skill and diligence usually possessed and exercised by physicians similarly situated. In other words, while in the absence of statutory regulation, the door of the profession is open to all, the one who enters cannot escape the common law responsibility for his acts.1
Hutchins, Harry B. "Characteristics and Constitutionality of Medical Legislation." Mich. L. Rev. 7 (1909): 295-317.