Without question, Wisconsin courts have subject matter jurisdiction over all actions affecting the family, whether such orders are entered by this state or elsewhere. And child support is an action affecting the family. But just because a court has subject matter jurisdiction over an action does not mean it can exercise its judicial powers. The court must also have competency to proceed. Competency is not synonymous with subject matter jurisdiction.
Competency is a narrower concept.
In Wisconsin, competency is defined as the power of the court to exercise its subject matter jurisdiction in a given matter. So although a court is vested with subject matter jurisdiction by the constitution, the legislature may enact statutes limiting a court's exercise of subject matter jurisdiction. Such a legislative enactment affects that courts' competency to proceed rather than its subject matter jurisdiction. The case at bar involves the modification of a child support order issued in another state. We have already stated that Wisconsin courts have subject matter jurisdiction over all child support orders, including those issued by other states.