G.R. No. 199371 - Petron LPG Dealers Association vs. Ang

Petitioners, represented by LPG dealers’ associations (Petron LPG Dealers Association and Total Gaz LPG Dealers Association), alleged that respondents were engaged in illegal trading and unauthorized refilling of LPG cylinders.
They claimed that Nation Gas, represented by its agents and occupants, refilled branded LPG cylinders (Shellane, Gasul, Totalgaz, Starflame, and Superkalan Gaz) without the required written authorization from the respective brand owners.
The allegations further included that the refilling involved underfilling of the LPG cylinders, violating Sections 2 (a) and (c) in relation to Sections 3 and 4 of Batas Pambansa Blg. 33 as amended by Presidential Decree No. 1865.

Petitioners filed a letter-complaint with the National Bureau of Investigation (NBI) – Ilocos Regional Office requesting surveillance, investigation, and arrest of the alleged offenders.
The complaint specifically detailed the purported illegal trading and unauthorized refilling, citing the statutory provisions and penalties under BP 33, as amended.
Supporting documents, including written certifications from LPG companies and evidence regarding the inadequacy of authorization by Nation Gas, were submitted as part of the complaint.

NBI agent Marvin de Jemil, along with undercover asset Leonardo Antonio, conducted surveillance based on the information provided by petitioners.
On November 24, 2005, the agents followed a truck from Barba Gas Marketing Center in Vigan City to a fenced compound in Magsingal, Ilocos Sur, identified as an LPG refilling plant allegedly operated by Nation Gas.
After observing the movement of the truck and the unloading of purportedly refilled LPG cylinders, the agents conducted a test-buy operation at the Barba Gas sales office where an exchange of an empty 11-kg. cylinder for a filled one was made.
The test-buy transaction was documented through a receipt, weighing, inspection, photographic evidence, and subsequent analysis of the cylinder, reinforcing the claim of underfilling and unauthorized sealing.

Based on the surveillance and test-buy evidence, applications for search warrants (Nos. 2005-59 and 2005-60) were filed in the Regional Trial Court (RTC) of Bauang, La Union.
The RTC, after receiving testimonies (including from De Jemil and Antonio) and related documentary evidence, issued the search warrants and executed the search at the refilling plant, seizing items subsequently inventoried.
Respondents filed a Motion to Quash arguing lack of probable cause, insufficiency of personal knowledge by the NBI agents, and other procedural irregularities.
On August 4, 2006, the RTC quashed the search warrants, finding that the witnesses lacked personal knowledge and that the evidence did not establish probable cause.
Petitioners then appealed the RTC decision before the Court of Appeals (CA), which on September 2, 2011, rendered a decision sustaining the RTC’s ruling, subsequently denying the petitioners’ appeal and motion for reconsideration in November 2011.

Petitioners filed a Petition for Review on Certiorari challenging the CA’s decision.
The central contention advanced was that the CA erred in finding that NBI agents and their witnesses lacked personal knowledge to establish probable cause.
Petitioners argued that the surveillance, test-buy operations, and supporting documents conferred sufficient personal knowledge and evidence to justify the issuance of the search warrants.
The case raised important questions regarding the standards for establishing probable cause and the role of personal knowledge in the issuance of search warrants.

Whether the NBI agents, through their surveillance and test-buy operations, acquired sufficient personal knowledge of the alleged illegal activities to satisfy the requirements for establishing probable cause.
Whether the issuance of the search warrants was justified given that the evidence, including written certifications and physical evidence from the test-buy, sufficiently established probable cause.
Whether the Court of Appeals erred in affirming the RTC’s ruling that quashed the search warrants on the basis of the agents’ lack of personal knowledge and insufficient verification of the alleged offenses.
Whether the isolated incident of underfilling, when examined in the totality of the evidence, constitutes a violation under BP 33, as amended, thereby warranting the issuance of a search warrant.