Michigan Compiled Laws, Chapter 700. Estates and Protected Individuals Code § 700.5318

Sec. 5318. If a third person is dealing with a guardian or is assisting a guardian in the conduct of a transaction, the third person may assume the existence of trust powers and their proper exercise by the guardian without inquiry. The third person is not bound to inquire whether the guardian may act or is properly exercising the power. Unless the third person has actual knowledge that the guardian is exceeding the guardian's powers or improperly exercising them, a third person is fully protected in dealing with the guardian as if the guardian possessed and properly exercised the powers the guardian purports to exercise. A third person is not bound to assume the proper application of estate assets paid or delivered to the guardian. This section does not apply to a third person dealing with a limited guardian.