Welcome, and thanks for looking inot open carry. There is no law that allows open carry, its just that there is NO law to prohibit open carry.
Many people have called/asked LEO's across the state to see if open carry is legal. There are some LEO's that are either unaware that it is legal, or they just try to discourage people from open carrying. Sometimes you may be asking a clerical worker that is unaware that OC (open carry) is legal. I understand you are probably just trying to cover all your bases before you (possibly) OC by asking your local police if they are aware of it and know it's legal, but many times it is pointless. You could send them(or deliver in person)an "LEO PACKET" (which is one of the threads "sticked" on this forum. This way you know they recieved the pamphlet informing them that OC is in fact legal. This will help you if you are ever faced with a court battle for lawfully carrying (just make sure you are folloing the letter of the law to a "T").
Please make sure you are aware of the laws and rules you must follow before you decide to open carry. Start off by reading the topic WASH,RINSE,REPEAT that is "stickied" on the Michigan forums homepage of opencarry.org
Hope this helps!