§ 90.04  AGE OF PURCHASER.
   (A)   Alcoholic liquor shall not be  sold or furnished to a person unless the person has attained 21 years of age. A person who knowingly sells or furnishes alcoholic liquor to a person who is less than 21 years of age, or who fails to make diligent inquiry as to whether the person is less than 21 years of age, is guilty of a violation of this code. A suitable sign which describes this section and the penalties for violating this section shall be posted in a conspicuous place in each room where alcoholic liquors are sold. The signs shall be approved and furnished by the Liquor Control Commission.
   (B)   If a violation occurs in an establishment that is licensed by the Liquor Control Commission for consumption of alcoholic liquor on the licensed premises, a person who is a licensee or the clerk, agent or employee of a licensee shall not be charged with a violation of division (A) unless the licensee or the clerk, agent or employee of the licensee knew or should have reasonably known with the exercise of due diligence that a person less than 21 years of age possessed or consumed alcoholic liquor on the licensed premises and the licensee or clerk, agent or employee of the licensee failed to take immediate corrective action.
   (C)   If the enforcing agency involved in the violation is the state police or the city’s Police Department, a licensee shall not be charged with a violation of division (A) unless the enforcement action under § 90.05 is taken against the person less than 21 years of age who purchased or attempted to possess alcoholic liquor and, if applicable, enforcement action is taken under this section against the person 21 years of age or older who sold or furnished the alcoholic liquor to the person who is less than 21 years of age. If the enforcing agency is the Liquor Control Commission, then the Liquor Control Commission shall recommend to the Police Department that enforcement action be taken against a violator of this section or § 90.05 who is not a licensee.  However, this division (C) does not apply under any of the following circumstances:
      (1)   The person against whom enforcement action is taken under § 90.05 or the person 21 years of age or older who sold or furnished alcoholic liquor to the person less than 21 years of age is not alive or is not present in this state at the time the licensee is charged;
      (2)   The violation of division (A) is the result of an undercover operation in which the person less than 21 years of age purchased or received alcoholic liquor under the direction of the person’s employer and with the prior approval of the local prosecutor’s office as part of an employer-sponsored internal enforcement action; or
      (3)   The violation of division (A) is the result of an undercover operation in which the person less than 21 years of age purchased or received alcoholic liquor under the direction of the state police, Liquor Control Commission, or a local police agency as part of an enforcement action. However, any initial or contemporaneous purchase or receipt of alcoholic liquor by the person less than 21 years of age shall have been under the direction of the state police, Liquor Control Commission, or the local police agency and shall have been part of the undercover operation.
   (D)   If a person less than 21 years of age participates in an undercover operation in which the person less than 21 years of age is to purchase or receive alcoholic liquor under the supervision of a law enforcement agency, his or her parents or legal guardians shall consent to the participation if that person is less than 18 years of age.
   (E)   In an action for a violation of this section, proof that the defendant or the defendant’s agent or employee demanded and was shown, before furnishing alcoholic liquor to a person under 21 years of age, a motor vehicle operator’s license or a registration certificate issued by the federal selective service, or other bona fide documentary evidence of the age and identity of that person, shall be a defense to an action brought under this section.
   (F)   As used in this section:
      CORRECTIVE ACTION.  The term means action taken by a licensee or a clerk, agent or employee of the licensee designed to prevent a person less than 21 years of age from further possessing or consuming alcoholic liquor on the licensed premises. The term includes but is not limited to contacting a law enforcement agency and ejecting the person less than 21 years of age and any other person suspected of aiding and abetting the person less than 21 years of age.
      DILIGENT INQUIRY.  The term means a diligent good faith effort to determine the age of a person, which includes at least an examination of an official state operator’s license, an official state identification card, or any other bona fide picture identification which establishes the identity and age of the person.
(M.C.L.A. § 436.33)  Penalty, see § 10.99