G.R. No. 243167 . June 28, 2021.
The Municipality of Payao, Zamboanga Sibugay, Petitioner, vs. The Municipality of Imelda, Zamboanga Sibugay, Respondent.

FACTS

The Municipalities of Payao and Imelda, created by Presidential Decree Nos. 1238 and 1239 respectively in 1977, have a long-standing territorial and jurisdictional controversy over Barangay Guintolan, which is situated along their adjacent boundaries. In 1987, the Sangguniang Panlalawigan (SP) of Zamboanga del Sur issued Resolutions approving the transfer of Barangay Guintolan from Payao to Imelda. Payao filed a Petition for Declaratory Relief, and the RTC-Pagadian, Branch 19 declared the SP Resolutions null and void, holding that municipal boundaries can only be altered by an act of the Batasang Pambansa. In 2001, Imelda filed its first Petition for Mandamus against Payao before the RTC-Pagadian, Branch 21, which was dismissed, holding that based on the municipal charters, jurisdiction over Barangay Guintolan belonged to Payao. Imelda then sought recourse before the Sangguniang Panlalawigan of Zamboanga Sibugay, which advised filing a court case. Consequently, in 2011, Imelda filed a second Petition for Mandamus before the RTC-Imelda, Branch 31, attaching certified Official Gazette copies of the municipal charters and a DENR Base Map showing Barangay Guintolan within Imelda’s territory. The RTC-Imelda granted the mandamus petition, decreeing Barangay Guintolan under Imelda’s jurisdiction and ordering Payao to cease and desist from exercising control and to peacefully turn over the barangay. The Court of Appeals affirmed the RTC decision. Payao appealed to the Supreme Court, arguing that mandamus is an improper remedy and that the second petition is barred by res judicata.

ISSUE

1. Whether mandamus is an appropriate remedy for the Municipality of Imelda to obtain jurisdiction over Barangay Guintolan.
2. Whether the second Petition for Mandamus filed by the Municipality of Imelda is barred by res judicata.

RULING

The Supreme Court denied Payao’s Petition for Review on Certiorari, ruling that mandamus was a proper remedy and that res judicata did not apply.
1. On the propriety of mandamus: The Court held that mandamus under Section 3, Rule 65 of the Revised Rules of Court is of two types: to compel the performance of a clear legal duty, or as a remedy against unlawful exclusion from the use and enjoyment of a right or office. The present case falls under the second type. The Court articulated that mandamus against unlawful exclusion is proper to restore a petitioner to a right or office to which they are entitled. The Municipality of Imelda, by virtue of its charter (P.D. No. 1239) which explicitly enumerates Barangay Guintolan as one of its constituent barangays, has a clear legal right to exercise jurisdiction over it. The DENR Base Map further corroborated this territorial delineation. Payao’s exercise of jurisdiction, based on erroneous copies of the charters, constituted an unlawful exclusion of Imelda from its right. Mandamus was the appropriate remedy to rectify this exclusion, as there was no other plain, speedy, and adequate remedy in the ordinary course of law.
2. On the application of res judicata: The Court ruled that res judicata did not bar the second mandamus petition. For res judicata to apply, there must be: (a) a final former judgment; (b) rendered by a court with jurisdiction; (c) a judgment on the merits; and (d) identity of parties, subject matter, and causes of action between the first and second actions. The Court found no identity of causes of action. The first mandamus case (2001) was dismissed by the RTC-Pagadian, Branch 21 based on copies of the municipal charters certified only by the National Library’s Filipiniana Division. The second mandamus case (2011) was based on newly presented evidence—certified true copies from the Official Gazette and a DENR Base Map—which were not considered in the first case. This new evidence fundamentally altered the cause of action and established Imelda’s clear right. Furthermore, the Court noted that the first mandamus case was dismissed based on an erroneous premise (the uncertified charters), and applying res judicata would perpetrate a miscarriage of justice. Therefore, the second petition was not barred.