Mich. Comp. Laws § 423.508

Sec. 8. (1) An employer shall not gather or keep a record of an employee's associations, political activities, publications, or communications of nonemployment activities, except if the information is submitted in writing by or authorized to be kept or gathered, in writing, by the employee to the employer. This prohibition on records shall not apply to the activities that occur on the employer's premises or during the employee's working hours with that employer that interfere with the performance of the employee's duties or duties of other employees. (2) A record which is kept by the employer as permitted under this section shall be part of the personnel record.