Mich. Comp. Laws § 338.836

Sec. 16. (1) A person shall not possess or display a badge or shield that purports to indicate that the holder is a private detective, private investigator, or professional investigator. (2) A licensee may request authorization to provide employee identification cards only upon the express authorization of the department as to format and content. (3) A person shall not display any badge, shield, identification card, or license that might mislead the public into thinking that the holder is a licensed professional investigator. (4) A person who violates this section is guilty of a misdemeanor and any unauthorized badge, shield, identification card, or license shall be confiscated by any law enforcement officer of the state. Each day the violation continues shall constitute a separate offense.