West Virginia Code Chapter 50. Magistrate Courts § 50-4-9. Counterclaim

A defendant in a civil action may file a counterclaim and if such counterclaim arises from the same transaction or occurrence that is the subject matter of the initial claim they shall be tried together. The failure to institute a counterclaim permitted by this section shall not preclude the institution of an action on such claim at a later date. The adjudication of the original claim shall not constitute res judicata as to any such permitted counterclaim nor shall it act as an estoppel as to such permitted counterclaim.