Mich. Comp. Laws § 600.2912a

Sec. 2912a. (1) Subject to subsection (2), in an action alleging malpractice, the plaintiff has the burden of proving that in light of the state of the art existing at the time of the alleged malpractice: (a) The defendant, if a general practitioner, failed to provide the plaintiff the recognized standard of acceptable professional practice or care in the community in which the defendant practices or in a similar community, and that as a proximate result of the defendant failing to provide that standard, the plaintiff suffered an injury. (b) The defendant, if a specialist, failed to provide the recognized standard of practice or care within that specialty as reasonably applied in light of the facilities available in the community or other facilities reasonably available under the circumstances, and as a proximate result of the defendant failing to provide that standard, the plaintiff suffered an injury. (2) In an action alleging medical malpractice, the plaintiff has the burden of proving that he or she suffered an injury that more probably than not was proximately caused by the negligence of the defendant or defendants. In an action alleging medical malpractice, the plaintiff cannot recover for loss of an opportunity to survive or an opportunity to achieve a better result unless the opportunity was greater than 50%.