Legal Question in Landlord & Tenant Law in Michigan

Did you look at the property before signing the lease? Did this mold suddenly appear, right after you moved in?

First, you should determine what sort of mold this is. Not all molds are toxic. In fact, toxic black mold has gotten a lot of "press" so people are now convinced that all molds are dangerous. The answer to your question depends on what type of mold it is and where it is located. If it's in an accessible spot, it may just be mildew, the sort you get in bathrooms and you can spray it with diluted bleach. If it's in the attic or between the walls, then it's a harder to treat situation. Unless the mold presents some sort of a health hazard or impacts the habitability of the home, it sounds like it's a housekeeping issue.

Your lease should state that the lease may be terminated in the event that the house becomes uninhabitable. Read your lease. If your lease states that uninhabitability terminates the lease, then what he said is not illegal.