Insights · Chain of custody

Chain of custody for digital video, explained

September 2024 · 4 minute read

With physical evidence, chain of custody is a sign-out sheet. With digital video, it is something subtler: a provable account of where a file came from and that it has not been changed.

Courts increasingly rely on technical markers to establish that. Under Federal Rule of Evidence 902, electronic data can be self-authenticated through a process of digital identification, typically a hash value, a unique string generated from the contents of a file. If the original and a copy share the same hash, they are demonstrably identical. The American Bar Association has described how these rules to authenticate digital evidence without a live witness.

Why the original file matters

All of this depends on starting from the original. A file pulled straight off the recording device carries the metadata and integrity that authentication relies on. A re-exported, re-saved, or messenger-compressed copy often strips that record away, and with it, the easiest path to proving when the footage was captured.

The shorter and better-documented the path from camera to courtroom, the harder the footage is to challenge. Fewer hands, fewer conversions, and a verifiable timestamp are what keep a chain of custody clean.