Mich. Comp. Laws § 600.2117: Device by way of seal as evidence of seal.

Sec. 2117.

Any device affixed to any deed or instrument in writing by way of seal, by any person signing the same, executed since the thirty-first day of December, 1827, or hereafter to be executed, shall be received in all courts, and upon all occasions as evidence that the same deed or instrument was duly sealed, and equally valid and effectual, as if the same had been actually sealed; but this section shall not apply to official and corporate seals, in cases where, according to law, an actual sealing may be required.