Regulation of Forensic Sample Chain-of-Custody Requirements in China

1. Legal Framework

China regulates the collection, preservation, transfer, examination, and presentation of forensic samples through criminal procedure legislation, judicial interpretation, and technical standards. The Criminal Procedure Law of the People’s Republic of China, together with rules governing forensic appraisal (司法鉴定), establishes the principal legal framework for ensuring the authenticity and reliability of physical and biological evidence.

The major legal instruments include:

Criminal Procedure Law (2018 revision): Governs the collection, examination, verification, and admissibility of evidence in criminal proceedings.

Provisions on Several Issues Concerning the Implementation of the Criminal Procedure Law (2021): Provide procedural rules for criminal cases, including the handling and examination of evidence.

Rules on Criminal Procedure of Public Security Organs (2020): Regulate evidence collection, seizure, preservation, and investigative procedures by public security authorities.

General Principles of Judicial Appraisal Procedures (2007): Establish general requirements for forensic appraisal institutions and appraisers.

Judicial Appraisal Procedures (2016): Regulate the acceptance, implementation, and documentation of judicial appraisal activities.

People’s Court Rules on Evidence in Criminal Cases: Include requirements for examining physical evidence, documentary evidence, expert opinions, and other materials presented at trial.

These instruments collectively support the principle that forensic evidence must be lawfully obtained, properly documented, and capable of verification.

2. Meaning and Importance of Chain of Custody

Chain of custody refers to the documented history of a forensic sample from its initial collection to its examination, storage, transfer, and presentation in court. It establishes who collected the sample, when and where it was collected, how it was sealed, who handled it, and whether its integrity was maintained.

In China, chain-of-custody documentation is particularly important for DNA samples, bloodstains, biological tissues, toxicological specimens, fingerprints, and other physical evidence.

The principal requirements generally include:

Lawful collection: Samples must be collected by authorized personnel in accordance with applicable procedural requirements.

Accurate identification: Each item should be assigned an identifiable reference number and described in the evidence records.

Sealing and packaging: Packaging must protect the sample from contamination, deterioration, substitution, and unauthorized access.

Transfer documentation: Transfers between investigators, storage facilities, laboratories, and forensic experts should be recorded.

Secure storage: Biological samples should be stored under suitable conditions, with access controlled and documented.

Examination records: Laboratories should maintain records of receipt, condition, testing procedures, results, and any remaining material.

Court verification: The prosecution and court must be able to assess whether the sample presented is the same material originally collected and whether its integrity was maintained.

A minor clerical error does not automatically invalidate evidence. The importance of a defect depends on whether it affects authenticity, reliability, legality, or the ability to verify the evidence.

3. Statutory Rules on Evidence Integrity

Under China's Criminal Procedure Law, evidence must be verified before it can serve as the basis for a judicial decision. Article 50 identifies categories of evidence, including physical evidence, expert opinions, and inspection or examination records. Article 55 establishes the requirement that a conviction must be supported by evidence that has been verified and that the evidence must be sufficient to exclude reasonable doubt.

These provisions are central to chain-of-custody disputes. If a biological sample has an unexplained break in its documented history, the court may question whether the test result reliably relates to the accused or the alleged offence.

The Rules on Criminal Procedure of Public Security Organs provide more detailed requirements for investigative handling of evidence, including the preparation of records, sealing, registration, and preservation. Forensic appraisal rules also require appraisal institutions to examine the materials received and assess whether they are suitable for the requested examination.

Where a sample arrives with damaged packaging, inconsistent identification numbers, or unexplained discrepancies, the receiving institution's assessment and documentation become particularly important.

4. Consequences of Chain-of-Custody Violations

Chinese courts assess evidentiary defects according to their nature and seriousness.

Minor, explainable irregularities: Evidence may remain usable if its identity and integrity can be reliably established.

Serious authenticity concerns: The court may refuse to rely on the evidence if the defect cannot be satisfactorily explained or corrected.

Unlawful collection: Evidence may be excluded where applicable statutory exclusionary rules are triggered.

Unreliable forensic appraisal: An expert opinion may be rejected or given reduced weight if its underlying materials, methods, or conclusions cannot be verified.

Article 56 of the Criminal Procedure Law addresses exclusion of illegally obtained evidence, including specified forms of unlawfully obtained physical and documentary evidence where the statutory conditions are met. The exclusionary framework should not be confused with a rule that every chain-of-custody mistake automatically requires exclusion.

Potential consequences for responsible personnel may also arise under applicable disciplinary, administrative, or criminal laws if evidence is deliberately substituted, destroyed, fabricated, or falsified.

5. Case Laws and Judicial Application

A. Criminal Procedure Law: Verification of Evidence

Articles 50, 55, and 56 of the Criminal Procedure Law form the statutory foundation for judicial review of forensic evidence.

Legal principle: Physical and biological evidence must be verified, and serious defects affecting authenticity or reliability can prevent a court from relying on the evidence. Article 56 is particularly relevant where the problem concerns unlawful collection rather than merely incomplete documentation.

These provisions are statutory authorities, not individual judicial precedents.

B. DNA Evidence and Sample Identity Disputes

In criminal cases involving DNA evidence, the central questions include whether the sample was correctly identified, whether contamination or substitution was possible, and whether the expert opinion is supported by reliable underlying materials.

Legal principle: A DNA match is not automatically conclusive if the provenance of the tested material is uncertain. Courts must consider the forensic result alongside collection records, appraisal documentation, other evidence, and any explanation for discrepancies.

A particular Chinese DNA case should only be cited by name, court, case number, and judgment date after the judgment has been verified. Without those details, describing a hypothetical DNA dispute as an actual precedent would be misleading.

C. Judicial Appraisal Procedures

China's judicial appraisal framework requires forensic institutions to assess the materials submitted for examination and conduct appraisal in accordance with applicable professional and procedural standards.

Legal principle: The reliability of an expert opinion depends not only on scientific methodology but also on the suitability and traceability of the materials examined. Deficiencies in the source material may undermine the evidentiary value of the resulting opinion.

Again, these procedural rules provide legal authority, but they should not be represented as a named court judgment.

6. Conclusion

China's forensic chain-of-custody framework is based on lawful evidence collection, reliable identification, documented transfers, secure preservation, and judicial verification. The Criminal Procedure Law establishes the overarching evidentiary requirements, while public security procedures and judicial appraisal rules govern practical handling and examination.

The central legal principle is that the authenticity and reliability of a forensic sample must be capable of verification throughout its evidentiary history. A chain-of-custody defect does not automatically make evidence inadmissible; its effect depends on the seriousness of the defect, the available explanation, and the applicable exclusionary rules.

For academic work, Articles 50, 55, and 56 of the Criminal Procedure Law are useful primary authorities. Specific Chinese judgments should be added only after verification through an official court database, such as the Supreme People's Court's judicial case database, to avoid citing unverified or inaccurately described precedents.