The "Michigan Medical Treatment Decisions Act" establishes a framework for making medical treatment decisions on behalf of patients who are unable to participate in such decisions. The bill defines key terms such as "attending physician," "guardian," "patient advocate," and "surrogate," and outlines the hierarchy of individuals who may make medical treatment decisions, prioritizing spouses, adult children, parents, and other relatives or friends. It stipulates that these decisions can only be made when the patient is unable to participate, and there is no available patient advocate or guardian. Additionally, the attending physician must document the patient's inability to participate and ensure that the patient's known desires and religious beliefs are respected in the decision-making process.

The bill also prohibits certain types of medical treatments from being authorized by the designated individuals, including the withholding or withdrawing of treatment that would result in the patient's death, sterilization, termination of pregnancy, and admission to specific types of facilities. Furthermore, it clarifies that healthcare providers implementing decisions made under this act will be held liable as if the patient had made the decision themselves. The act does not override existing advance directives or patient advocate designations, ensuring that previously expressed wishes regarding medical treatment are honored.