"x x x.
On this point, our disquisition in Spouses Atuel v. Spouses Valdez[16] is instructive, thus:
Jurisdiction over the subject matter cannot be acquired through, or waived by, any act or omission of the parties. The active participation of the parties in the proceedings before the DARAB does not vest jurisdiction on the DARAB, as jurisdiction is conferred only by law. The courts or the parties cannot disregard the rule of non-waiver of jurisdiction. Likewise, estoppel does not apply to confer jurisdiction to a tribunal that has none over a cause of action. The failure of the parties to challenge the jurisdiction of the DARAB does not prevent this Court from addressing the issue, as the DARAB’s lack of jurisdiction is apparent on the face of the complaint. Issues of jurisdiction are not subject to the whims of the parties.
In a long line of decisions, this Court has consistently held that an order or decision rendered by a tribunal or agency without jurisdiction is a total nullity. Accordingly, we rule that the decision of the DARAB in the instant case is null and void. Consequently, the decision of the Court of Appeals affirming the decision of the DARAB is likewise invalid. This Court finds no compelling reason to rule on the other issues raised by the Spouses Atuel and the Spouses Galdiano.[17] (Citations omitted and emphases supplied)
x x x."
