§1. If an exception is proposed against the competence of the judge, that judge must deal with the matter.
§2. In the case of an exception of relative incompetence, if the judge finds for competence, the decision does not admit of appeal; a complaint of nullity and restitutio in integrum, however, are not prohibited.
§3. If the judge finds for incompetence, however, the party who feels injured can appeal to the appellate tribunal within fifteen useful days.
Source: Code of Canon Law (Vatican.va)