What non-inclusion in CERTIORARI petition makes it defective?

Indeed, petitioners have a plain and speedy remedy in the ordinary course of law as prescribed in Section 12 above. They cannot avail of certiorari as a substitute for that plain and speedy recourse. The writ of certiorari and prohibition may be availed of only when there is no appeal, or any plain, speedy, and adequate remedy in the ordinary course of law.

Second, even assuming that petitioners may resort to certiorari and prohibition, their petition, however, suffers from a fatal defect, i.e., it failed to implead the two concessionaires who are certainly indispensable parties. Indispensable parties are those which have such interest in the controversy that a final adjudication of the case would certainly affect their rights, so that the court cannot proceed without their presence. Thus, their non-inclusion in the petition for a writ of certiorari would render the said petition defective. (G.R. No. 173044; December 10, 2007)