G.R. No. 233480 , June 20, 2018
People of the Philippines, Plaintiff-Appellee, v. Melanie B. Mercader, Accused-Appellant.

FACTS

Accused-appellant Melanie B. Mercader was charged with illegal sale and illegal possession of dangerous drugs under Republic Act (R.A.) No. 9165. The prosecution’s case relied on evidence seized during a buy-bust operation. However, the records revealed significant procedural lapses in the handling of the seized items following her arrest.
The marking of the seized items was not conducted in the presence of any of the required witnesses—an elected public official, a representative from the Department of Justice (DOJ), or a media representative. Furthermore, the prosecution failed to provide any justifiable reason for this non-compliance. Conflicting statements from the police officers also cast doubt on whether the mandatory inventory and photographing of the seized items were ever conducted, as no such documentary evidence was presented or offered before the trial court.

ISSUE

Whether the procedural lapses in the chain of custody, specifically the non-compliance with the witness requirement and inventory procedures under Section 21 of R.A. No. 9165 , warrant the acquittal of the accused.

RULING

Yes, the acquittal is warranted. The Supreme Court, through the ponencia and concurred with by Justice Peralta, acquitted Mercader due to the prosecution’s failure to establish an unbroken chain of custody. The legal logic centers on the imperative duty of the prosecution in drug cases to prove not just the elements of the crime but also the integrity and identity of the corpus delicti. Section 21 of R.A. No. 9165 , and its amendment by R.A. No. 10640 , establishes a strict procedure—including inventory and photography in the presence of insulating witnesses—precisely to prevent planting, contamination, or switching of evidence.
The concurring opinion emphasized that while R.A. No. 10640 later relaxed the rule by requiring only two witnesses (an elected official and either a DOJ or media representative), and provided a saving clause for justifiable non-compliance, these amendments do not excuse the total disregard of the procedure absent any explanation. Here, the complete absence of the required witnesses during the critical post-seizure steps, coupled with the failure to justify such lapse and the lack of inventory reports, fatally compromised the evidence’s integrity. Without the proper safeguards, the identity of the drugs allegedly seized from the accused cannot be established with moral certainty, giving rise to reasonable doubt. The Court thus upheld the constitutional presumption of innocence, as the prosecution did not overcome this doubt regarding the corpus delicti’s identity.