Chain of Custody Imperative: Safeguarding Drug Evidence Integrity in Philippine Law

In drug cases, the prosecution must prove not only that the accused sold or possessed illegal drugs, but also that the very items presented in court are the same ones seized from the accused. This is the essence of the chain of custody rule. In People v. Coreche (G.R. No. 182528, August 14, 2009), the Supreme Court acquitted Marian Coreche y Caber of drug charges because the prosecution failed to establish an unbroken chain of custody over the seized shabu, creating reasonable doubt about the authenticity of the evidence.

The Facts of the Case

In the early morning of September 10, 2003, police officers in San Mateo, Rizal conducted a sting operation against appellant, who was suspected of selling shabu. A police officer and an informant posed as buyers. After appellant handed over a plastic sachet of suspected shabu in exchange for marked bills, she was immediately arrested. Police recovered two more plastic sachets from her possession.

The seized items were later submitted to the crime laboratory, which confirmed they contained methamphetamine hydrochloride, or shabu. Appellant was charged with illegal sale and illegal possession of dangerous drugs under Sections 5 and 11, Article II of Republic Act No. 9165, the Comprehensive Dangerous Drugs Act of 2002. Both the trial court and the Court of Appeals convicted her, relying heavily on the presumption of regularity in the performance of official duties by the police officers.

The Issue

The central issue was whether the prosecution had proven appellant's guilt beyond reasonable doubt, particularly whether the chain of custody of the seized drugs had been properly established.

The Ruling: Acquittal on Reasonable Doubt

The Supreme Court reversed the conviction and acquitted appellant. The Court ruled that the prosecution failed to prove the corpus delicti—the body of the crime—because of substantial gaps in the chain of custody of the seized drugs.

First Gap: Failure to Mark at the Arrest Site

The Court emphasized that marking the seized drugs immediately after seizure is the starting point of the custodial link. Marking serves to separate the evidence from all other similar items and prevents switching, planting, or contamination.

In this case, while the plastic sachets were marked "HVA, HVA-1, and HVA-2," there was no evidence showing when and where the marking was done. The arresting officer's testimony did not specify the time and place of marking. Meanwhile, another officer who arrested a co-accused clearly admitted he marked the sachet at the police station, not at the arrest site. This created a strong inference that the same irregularity occurred with appellant's seized items.

The Court cited previous rulings, including People v. Laxa and People v. Casimiro, holding that failure to immediately mark seized drugs raises reasonable doubt on the authenticity of the corpus delicti.

Second Gap: Unclear Post-Examination Custody

The prosecution also failed to clarify who had custody of the seized drugs after the laboratory examination. The stipulation between the parties merely stated that the specimens were placed in a plastic bag and initialed by the forensic chemist after testing. It did not state whether the specimens remained in his safekeeping or were transferred elsewhere before presentation in court.

This equivocal evidence left unanswered the question of post-examination custody, creating another substantial gap in the chain.

The Presumption of Innocence Prevails

The Court stressed that the presumption of regularity in the performance of official duties is not conclusive. It can be rebutted by contrary proof, and it is inferior to the constitutional presumption of innocence. Where substantial gaps exist in the chain of custody, reasonable doubt arises, and the accused must be acquitted.

Practical Takeaways

• Mark immediately. Police officers must mark seized drugs at the arrest site, in the presence of the accused, not later at the police station.
• Document every transfer. Prosecution must account for who held the drugs at every stage—from seizure to laboratory testing to presentation in court.
• Testify with specificity. Officers must testify clearly on when, where, and how the marking and custody transfers were done.
• Presumption is rebuttable. Courts must not automatically rely on the presumption of regularity; they must scrutinize the prosecution's evidence for gaps.
• For the accused. A broken chain of custody can be a valid defense, as it casts doubt on whether the drugs presented are truly the ones seized.

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