G.R. No. 198113 - People vs. Bautista y Sinaon

The dispute involves two local government units in Zamboanga Sibugay: the Municipality of Payao and the Municipality of Imelda.
Their creation and organization are governed, respectively, by Presidential Decree (PD) No. 1238 (Payao) and PD No. 1239 (Imelda), both issued in 1977.
Barangay Guintolan is geographically situated along the boundary between the two municipalities, giving rise to a jurisdictional controversy.

In 1987, upon a petition by the residents of Barangay Guintolan, the Sangguniang Panlalawigan (SP) of Zamboanga del Sur passed Resolutions (No. 166 and No. 188) transferring Barangay Guintolan from the Municipality of Payao to the Municipality of Imelda.
The Municipality of Payao then filed a Petition for Declaratory Relief and/or Nullification of Resolution No. 166 before the Regional Trial Court (RTC) of Pagadian City, which declared the resolution null and void on the ground that only an act of the Batasang Pambansa could alter a municipality’s boundaries.

In 2011, the Municipality of Imelda filed a Petition for Mandamus against the Municipality of Payao, along with various provincial officers, before the RTC of Ipil, Zamboanga Sibugay, docketed as Special Civil Action No. I-115.
Imelda submitted certified copies of the municipal charters and a Base Map from the DENR showing Barangay Guintolan within its territory.
The Municipality of Payao argued that mandamus was an improper remedy and that the case was barred by res judicata.

The RTC-Imelda ruled in favor of the Municipality of Imelda on April 1, 2015, ordering Payao to cease exercising jurisdiction over Barangay Guintolan and to effectuate the peaceful turnover of supervisory prerogatives.
The Municipality of Payao immediately filed a motion for reconsideration, which was denied by the RTC on May 22, 2015.
The Municipality of Payao then elevated the matter to the Court of Appeals, which in its Decisions dated February 28, 2018 and September 21, 2018, affirmed the RTC’s rulings, dismissing arguments regarding the improper remedy and res judicata.

The core dispute centers on which municipality holds the proper supervisory authority over Barangay Guintolan.
Imelda asserts that under PD No. 1239, Barangay Guintolan is expressly included as part of its jurisdiction, whereas Payao’s submission of erroneous copies of PD No. 1238 led to confusion regarding its own territorial claim.
The controversy is compounded by the protracted history of litigation and prior decisions that dealt with different issues—ranging from boundary disputes to the proper application of the municipalities’ charters.

Whether the writ of mandamus is the proper remedy for the Municipality of Imelda to enforce its supervisory right over Barangay Guintolan by compelling the Municipality of Payao to desist from exercising control and jurisdiction.

Whether the second Petition for Mandamus filed by the Municipality of Imelda is barred by the doctrine of res judicata given the previous related proceedings (i.e., the RTC-Pagadian and first mandamus case before the RTC of Pagadian).