KEABSAHAN TEKNIK PENYIDIKAN PEMBELIAN TERSELUBUNG (UNDERCOVER BUY) SEBAGAI ALAT BUKTI PADA TINDAK PIDANA NARKOTIKA

Abstract

This study examines the legality of the undercover buy investigative technique in narcotics offenses under Law Number 35 of 2009 on Narcotics. The central issue is the gap between formal legal procedures and field practices, where investigators often involve civilians as transaction executors due to identification and geographical constraints. Using an empirical legal method, the research draws on in-depth interviews with investigators from the Narcotics Investigation Unit of the Banjarbaru Police Resort and a former narcotics offender.

Findings show that under Article 75 letter (j) and Article 79 of the Narcotics Law, an undercover buy is legally valid only when conducted by an investigator with written assignment authorization. Involving civilians as buyers constitutes a formal procedural defect, violating the limits on public participation set out in Article 106. Sociological constraints—such as investigators being easily recognized in small communities—often drive these procedural deviations.

The study also highlights the reform under Article 16 paragraph (1) letter (f) of Law Number 20 of 2025 (the New Criminal Procedure Code), which formally classifies undercover buy as part of the investigative stage. The author concludes that the legality of evidence obtained through this technique is constitutive of compliance with legal-subject and administrative requirements, and recommends regulatory harmonization to accommodate urgent circumstances while upholding legality, human rights protection, and legal certainty.