Chain of Custody

Chain of custody refers to the chronological paper trail showing who collected, handled, transferred, analyzed, and stored a piece of evidence from the moment of seizure until its presentation in court. The concept is foundational in both domestic criminal procedure and international legal practice because evidence whose custody cannot be accounted for may be excluded as unreliable, tampered with, or contaminated.

In domestic systems, chain of custody is enforced through evidentiary rules requiring authentication before admission. In the United States, for example, Federal Rule of Evidence 901 requires a proponent to produce evidence sufficient to support a finding that the item is what it is claimed to be. Comparable authentication requirements exist in most common law and civil law jurisdictions.

In international criminal law, chain of custody has become a central concern for tribunals such as the International Criminal Court (ICC), the International Criminal Tribunal for the former Yugoslavia (ICTY), and the International Criminal Tribunal for Rwanda (ICTR). Investigators operating in conflict zones must document the collection of mass-grave remains, weapons fragments, intercepted communications, and increasingly open-source digital material such as satellite imagery and social media videos. The Berkeley Protocol on Digital Open Source Investigations (2022), published by the UN Office of the High Commissioner for Human Rights and the UC Berkeley Human Rights Center, sets out standards for preserving the provenance and integrity of online evidence.

Key elements typically required to establish a sound chain include:

• Identification: unique labeling of each item at the point of collection.
• Documentation: contemporaneous logs naming every person who handled the item, with date, time, and purpose.
• Secure storage: tamper-evident containers, restricted access, and audit trails.
• Hashing for digital evidence: cryptographic checksums (e.g., SHA-256) to verify that files have not been altered.

Breaks in the chain do not automatically render evidence inadmissible, but they go to weight and may give defense counsel grounds to challenge authenticity or argue for exclusion.