Not only are licenses legal proof that a dog belongs to you, but they are an excellent way for any individual to know if an animal has been vaccinated against rabies. Additionally, licenses allow for a lost or found pet to be returned to their rightful owner as soon as possible. Licensing your dog is also the law.
Michigan state law (MCLA 286.262) requires all dogs 4 months of age and older be licensed in the County in which they reside. Licenses must also be physically worn by dogs when they are outside of their home environment.