Incompetence of the tribunal is said to be absolute: a) when a tribunal is incompetent to hear the case due to the quality of the contested issue (e.g. a case concerning an administrative act placed in a judicial tribunal), b) when it is already pending in another court (e.g. a case which was taken up by another tribunal and has already cited the respondent), c) when it is concerning certain persons of dignity reserved to the apostolic tribunal (e.g. A case wherein an apostolic legate is a party), or d) when it is placed in a grade tribunal which cannot hear the case (e.g. a tribunal is appealed to a tribunal of first instance again).
If the judge acts under absolute incompetence, the sentence is null. Such a case can be challenged at any stage of the trial and the competent tribunal cannot use the acts of the case.
This principle is based on the motive of effective administration of justice in the church. In certain cases such as cases involving heads of State, cardinals, legates of the Apostolic See, bishops in penal cases and other cases that the Holy Father reserves to himself, the lower courts are absolutely incompetent for the reason that these courts would be intimidated and justice will be disparaged.