Chain of Custody in Drug Cases: Why Marking Evidence Immediately Matters

In drug cases, the seized substance is the very heart of the prosecution's case. Without it, there is no crime. That is why Philippine courts require the prosecution to establish an unbroken "chain of custody" — a documented trail showing that the drugs presented in court are exactly the same items seized from the accused. In Calma v. People (G.R. No. 180586, November 20, 2017), the Supreme Court acquitted an accused because the prosecution broke that chain. The case is a clear reminder that procedure is not mere formality; it protects the innocent from wrongful conviction.

The Facts of the Case

On March 6, 2002, police officers in Solano, Nueva Vizcaya conducted a buy-bust operation against Arnelio Calma. A police officer, acting as a poseur-buyer, purchased a sachet of suspected shabu from Calma for P1,000. After the exchange, the team arrested Calma and recovered another sachet from his wallet. The two sachets were brought to the police station, where an investigator marked them with his initials. They were later submitted to the crime laboratory, which confirmed the substance was methamphetamine hydrochloride.

Calma was charged with illegal sale of drugs under Section 15, Article III of Republic Act No. 6425, the Dangerous Drugs Act of 1972. Both the trial court and the Court of Appeals convicted him. He appealed to the Supreme Court.

The Issue

The central question was whether the prosecution proved Calma's guilt beyond reasonable doubt — specifically, whether it established an unbroken chain of custody over the seized drugs.

The Ruling

The Supreme Court reversed the conviction and acquitted Calma. While the Court noted that minor inconsistencies in witness testimony do not automatically destroy a case, it found serious lapses in how the drugs were handled.

First, the sachets were not marked immediately at the scene of the arrest. The poseur-buyer, who first held the sachet sold to him, did not mark it right after the operation. Instead, the team brought both sachets to the police station, where an investigator who was not part of the buy-bust team marked them. The Court stressed that marking should be done immediately upon confiscation and in the presence of the accused, because marking is the starting point of the custodial link.

Second, there was confusion over who actually had custody of the sachets before they reached the crime laboratory. The poseur-buyer testified that he and the investigator personally brought the drugs to the lab, but the request form showed a different officer received them from a different person. This created doubt about the identity and integrity of the items examined.

Third, there were glaring discrepancies in the weight of the drugs. The Information alleged 0.8 gram, the request for laboratory examination stated 0.08 gram, and the forensic chemist reported 0.23 gram. The chemist's explanation — that the substance alone weighed more than the substance plus its plastic sachets — was scientifically impossible. The Court found this unacceptable.

Because the chain of custody was broken, the Court ruled that reasonable doubt existed as to whether the sachets presented in court were the same ones seized from Calma. He was therefore acquitted.

Forfeiture of Seized Items

The Court also addressed the confiscated motorcycle and cellphone. Under Section 20 of R.A. No. 6425, proceeds and instruments of the crime may be forfeited in favor of the government. However, forfeiture is tied to conviction. Since Calma was acquitted, the Court ordered the return of items that are of lawful commerce.

Practical Takeaways

• Mark evidence immediately. In buy-bust operations, seized drugs must be marked at or near the place of arrest, in the presence of the accused, by the officer who confiscated them. Delaying marking until arrival at the station breaks the chain.
• Document every transfer. Every person who handles the evidence must be identified, and each transfer must be recorded. Gaps in custody create reasonable doubt.
• Verify quantities. The weight stated in the Information, the request for laboratory examination, and the chemistry report must be consistent. Unexplained discrepancies are fatal to the prosecution.
• Minor inconsistencies are tolerable; major breaks are not. Courts forgive small contradictions in testimony, but they will not ignore lapses that compromise the integrity of the corpus delicti.
• Forfeiture follows conviction. Seized property that is not illegal per se can only be forfeited if the accused is convicted.

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