Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 147, § 37

At any boxing, kickboxing, mixed martial arts or other unarmed combative sporting event, sparring match or exhibition there shall be in attendance at least 1 duly licensed physician, whose duty it shall be to observe the physical condition of the contestants and advise the referee or judges with regard thereto.  A competent physician who has at least 3 years of experience as a medical practitioner may be licensed.  No contestant shall be allowed to enter the ring unless a physician licensed under this section and section 35 certifies in writing that the contestant is physically fit to engage in the proposed contest.  The physician’s fee, as fixed by the commission, shall be paid by the licensee conducting the match or exhibition.