Chain of Custody in Drug Cases: Why Procedural Lapses Lead to Acquittal

In drug cases, the prosecution must prove not only that the accused sold or possessed illegal drugs, but also that the drugs presented in court are exactly the same items seized from the accused. The Supreme Court's decision in People v. Cayas (G.R. No. 206888, July 4, 2016) underscores this principle. The Court acquitted Maritess Cayas of illegal sale and possession of shabu because the police failed to follow the mandatory chain of custody rules under Section 21 of Republic Act No. 9165, the Comprehensive Dangerous Drugs Act of 2002.

The Facts of the Case

On October 8, 2003, police officers conducted a buy-bust operation against Cayas in Noveleta, Cavite, based on a validated drug watchlist. PO2 Ronquillo acted as the poseur-buyer and purchased P100.00 worth of shabu from Cayas. After the sale, the arresting team frisked her and found two additional plastic sachets of shabu.

The police brought Cayas and the seized items to the Noveleta Municipal Police Station. There, PO3 Genuino—who was not part of the buy-bust team—marked the plastic sachets. The items were later submitted to the crime laboratory, which confirmed they contained methamphetamine hydrochloride.

The Regional Trial Court convicted Cayas, and the Court of Appeals affirmed. Both lower courts relied heavily on the presumption of regularity in the performance of police duties.

The Issue: Was the Chain of Custody Preserved?

The Supreme Court asked whether the prosecution had proven beyond reasonable doubt that the drugs presented in court were the same items seized from Cayas. The Court answered no.

Section 21 of RA 9165 requires the apprehending team to physically inventory and photograph the seized drugs immediately after confiscation. This must be done in the presence of the accused or her representative, a representative from the media, a representative from the Department of Justice, and any elected public official. These witnesses must sign the inventory.

The Court's Ruling: Acquittal

The Court found several fatal gaps in the prosecution's evidence:

No physical inventory or photographs. The police turned over the seized sachets to PO3 Genuino at the station, but no inventory was ever conducted, and no photographs were taken.

Marking was delayed. The arresting officers failed to mark the sachets immediately upon seizure at the place of arrest. Marking should be done in the presence of the apprehended violator right after confiscation to ensure the items can be identified later in court.

Conflicting markings. The arresting officers testified that PO3 Genuino marked the sachets with "MC" and "MCC-P." However, the Request for Laboratory Examination and Chemistry Report showed different markings: "MC-BB 08 Oct 2003" and "MC-P-1" and "MC-P2." The prosecution never explained these discrepancies.

Unidentified courier. PO1 Padilla testified that he and his team brought the items to the crime laboratory, but the Request for Laboratory Examination showed they were delivered by a different officer, PO1 Goquila.

The Court emphasized that the presumption of regularity in police performance cannot override the constitutional presumption of innocence. The prosecution must prove its case on its own merits. When procedural lapses occur, the prosecution must acknowledge them and explain justifiable grounds, then prove that the integrity and evidentiary value of the drugs were preserved. Here, the prosecution did neither.

The Four Links of the Chain

The Court reiterated the four links that must be established in the chain of custody:

1. Seizure and marking of the illegal drug by the apprehending officer
2. Turnover of the drug to the investigating officer
3. Turnover by the investigating officer to the forensic chemist for examination
4. Turnover and submission of the marked drug from the forensic chemist to the court

Each person who handled the evidence must describe how and from whom it was received, what happened to it while in their possession, and the precautions taken to prevent tampering.

Practical Takeaways

• Mark immediately. The marking of seized drugs should be done at the place of arrest, in the presence of the accused, not at the police station.
• Document everything. Physical inventory and photographs are mandatory under Section 21, RA 9165. The required witnesses—media, DOJ, and an elected official—must be present and sign the inventory.
• Explain any lapse. If police fail to strictly comply, the prosecution must acknowledge the lapse, explain justifiable grounds, and prove the drugs' integrity was preserved.
• Consistency matters. Discrepancies in markings between testimonies and laboratory documents create reasonable doubt.
• Presumption of regularity is not enough. It is a mere rebuttable statutory presumption that cannot defeat the constitutional presumption of innocence.

This article is general information and not legal advice. For your specific situation, consult a lawyer or ask ASG Legal AI.