Michigan Compiled Laws, Chapter 440. Uniform Commercial Code § 440.4109

Sec. 4109. (1) Unless otherwise instructed, a collecting bank in a good faith effort to secure payment of a specific item drawn on a payor other than a bank and with or without the approval of any person involved, may waive, modify, or extend time limits imposed or permitted by this act for a period not exceeding 2 additional banking days without discharge of drawers or endorsers or liability to its transferor or any prior party.

(2) Delay by a collecting bank or payor bank beyond time limits prescribed or permitted by this act or by instructions is excused if (i) the delay is caused by interruption of communication or computer facilities, suspension of payments by another bank, war, emergency conditions, failure of equipment, or other circumstances beyond the control of the bank and (ii) the bank exercises such diligence as the circumstances require.