Glossary
Chain of custody
The documented account of who held an item of evidence, and when, from collection to examination and presentation.
Why the concept exists
An item only means something in court if the court can be sure it is the same item, unaltered, that was taken from the scene. Chain of custody is the record that makes that assurance checkable by someone who was not there — which is why it is documentation rather than physical security.
Where it operates
It runs from seizure through storage, transfer, examination and return, and every handover is a point at which the account can break. The record is what allows a defence to test handling and a laboratory to demonstrate that what it examined is what was collected. Because interpretation rests on the integrity of the item, a custody failure can defeat an otherwise sound examination entirely.
Worth knowing
A gap does not merely weaken evidence; it can remove it from a case entirely.
How far it travels
The principle is close to universal; the formalities are not. What must be recorded, who may sign, how long material is retained, and the consequence of a break — exclusion, reduced weight, or an argument for the jury — are set by national law and by laboratory accreditation requirements.
Worked examples
Systems this platform has researched. Each example shows how one country actually arranges this — including where it departs from the general pattern.
- United States
- The 2009 National Academy of Sciences review of American forensic science examined evidence handling as part of a system-wide critique, and its findings about the discipline’s research foundation are a critique of arrangements in one country rather than a global audit.
Where this connects
Sources
Strengthening Forensic Science in the United States: A Path Forward
National Research Council (National Academy of Sciences); hosted by the Office of Justice Programs, U.S. Department of Justice · Academic · 2009 · link verified 2026-07-23
Supports the finding that forensic disciplines varied widely in scientific foundation, standardisation, and quality assurance, and that interpretation of evidence varied between jurisdictions. Its findings concern the United States as of 2009; they do not describe forensic practice in other countries or the position today.
European Network of Forensic Science Institutes
ENFSI · Institutional (self-description) · link verified 2026-07-23
Institutional self-description. Supports the existence of a European network of forensic institutes engaged in quality assurance and best-practice work. Attributed in the text as the organisation's own account of itself.