Mich. Comp. Laws § 28.464

Sec. 14. (1) A governmental or law enforcement agency that identifies a firework that is in violation of this act shall secure the firework and immediately notify the department of the alleged violation. The department or law enforcement agency shall investigate the alleged violation for compliance with this act. (2) If the department or law enforcement agency determines through its investigation under subsection (1) that a violation of this act has occurred, except for a violation of section 6(2), the department or law enforcement agency may seize the firework as evidence of the violation. The department or law enforcement agency shall store, or cause to be stored, the evidence seized under this section pending disposition of any criminal or civil proceedings arising from the violation. If the person subject to criminal or civil proceedings under this section is found guilty, responsible, or liable for the violation, the person shall be required to pay the storage expense for the evidence seized.