Mich. Comp. Laws § 247.175

Sec. 5. The declaration in such action shall follow the order required by section 1 of this chapter, in describing such encroachment. The defendant may plead denying the encroachment in whole or in part, and may also deny the existence of a highway where such encroachment is claimed to be, but otherwise the legal existence of the highway shall not be questioned on the trial, and the fact of such encroachment, and where the true line of the highway is, shall only be tried.