From Length to Sequence: What’s Changing in Forensic DNA
For three decades, the “gold standard” of forensic DNA was Short Tandem Repeat (STR) profiling analyzed by Capillary Electrophoresis (CE). STR-CE gauges the length of DNA fragments across loci; matching lengths inform match probabilities that powered CODIS and solved thousands of cases. NGS (also called Massively Parallel Sequencing—MPS) instead reads the bases themselves (A, C, G, T), yielding richer detail. Think of CE as confirming make and model, whereas NGS reads the license plate, interior color, and bumper scratches. This depth can salvage degraded samples and untangle complex mixtures (three-plus contributors) better than legacy methods. Forensically purposed platforms (e.g., MiSeq FGx) are specifically designed for human identification workflows and mixed/low-template samples.
Admissibility: Reliability Versus Novelty
U.S. Inflection Point — People v. Adrian Chavez (California, 2024)
In January 2024, a California trial admitted NGS evidence after a pre-trial admissibility hearing concluded the technique was reliable and had general acceptance. The Kern Regional Crime Lab validated the MiSeq FGx workflow and used NGS to establish crime-scene location and circumstance in a double-homicide; a jury convicted Adrian Chavez. This was widely reported as the first successful U.S. admissibility of NGS data in a jury trial and has become persuasive authority that NGS is forensic-grade, not experimental.
The Indian Legal Lens: Where Does NGS Fit?
1) Statutory Framework (2024–25)
Bharatiya Sakshya Adhiniyam (BSA), 2023 — India’s new evidence law (in force from July 1, 2024) modernizes definitions, elevates electronic/digital records, and reorganizes expert evidence. Key points:
- Electronic/Digital Records: Sections 62–63 treat computer outputs as “documents” if certification conditions are met, effectively replacing old Section 65B regime.
- Expert Evidence: Section 39 recognizes opinions of experts in science/technology and explicitly covers electronic evidence (through IT Act §79A examiners). This modernizes the former Section 45 IEA.
- Government confirmation of commencement: BNS, BNSS, BSA notified Dec 25, 2023; BSA in force July 1, 2024.
BNSS, 2023 (new CrPC) complements BSA by mandating wider technology use, videography of crime scenes, and improved chain-of-custody practices—critical for scientific evidence integrity.
2) Case Law Foundations for Scientific Evidence
Indian courts have laid broad criteria that NGS must satisfy:
- Chain of Custody: Kishore Chand v. State of Himachal Pradesh (SC, 1990/91) underscored stringent standards for circumstantial/forensic evidence and documentation—any gap can undermine admissibility.
- DNA Reliability: Murugan @ Settu v. State of Tamil Nadu (SC, 2011) recognized DNA profiling’s probative strength when properly collected and presented.
- Non-Compulsion of Invasive “Mind” Techniques: Selvi v. State of Karnataka (SC, 2010) barred involuntary narco-analysis/polygraph/BEAP under Article 20(3), framing limits on compelled scientific procedures and emphasizing voluntariness and privacy.
These set a high bar: validated method, impeccable chain, and voluntary collection—principles that apply equally to NGS.
3) DNA, Privacy & Paternity: Guardrails from the Supreme Court
India’s Right to Privacy (Article 21) was constitutionalized in K.S. Puttaswamy v. Union of India (2017), shaping courts’ approach to genetic information. Privacy is fundamental but not absolute; interferences require legality, necessity, and proportionality
In paternity disputes, the Court has cautioned against routine DNA testing given privacy and dignity concerns and the presumption of legitimacy under Section 112 (old IEA)—now carried forward under the BSA framework. Recent 2025 rulings reiterate that DNA tests should be ordered only in exceptional cases and typically require proof of non-access between spouses; privacy harms and stigma weigh heavily.
Separately, the Delhi High Court’s Rohit Shekhar v. Narayan Dutt Tiwari line of cases illustrate that while courts can direct DNA testing in the public interest of truth, forcible extraction is impermissible; non-compliance may draw adverse inferences, but bodily autonomy remains protected. The Supreme Court facilitated confidential sampling via CDFD in 2012, balancing truth-seeking and privacy.
Implication for NGS in India: Where NGS is used for identification, admissibility hinges on validation, chain, statistical reporting, and transparency. Where NGS supports phenotyping (eye/skin/hair color, ancestry), courts will scrutinize privacy, bias risk, and whether such probabilistic traits are more prejudicial than probative under the BSA’s reliability and relevance tests.
Beyond Profiling: Forensic DNA Phenotyping (FDP) & the Privacy Quagmire
NGS-enabled SNP panels can predict traits (eye/hair/skin) and biogeographical ancestry. These outputs are probabilistic, not certainties, and may risk cognitive bias if presented unguardedly to juries (e.g., “90% likely blue eyes”). ENFSI/SWGDAM urge cautious validation, reporting standards, and transparency when novel markers are used.
In India, FDP usage in court is nascent. Any deployment must endure Article 21 privacy scrutiny post-Puttaswamy and align with BSA standards on expert testimony and electronic evidence. Phenotyping should be circumscribed to investigative leads unless and until robust validation, population representativeness, and calibration of error rates are established and disclosed.
Conclusion: Proceed with Caution, Not Fear
NGS is undeniably part of the forensic future, especially for degraded remains, complex mixtures, and identity SNPs. The U.S. Chavez ruling shows courts can admit NGS when science and validation are robust. For India, BSA/BNSS provide modernized evidence and procedure frameworks. The task now is to ensure method validation, software transparency, and privacy-respecting use—particularly for phenotyping—so NGS delivers justice without eroding rights.
Indian Policy Context: Data Banks & Regulation
India debated a dedicated DNA law for over a decade. The DNA Technology (Use and Application) Regulation Bill, 2019 proposed national/regional DNA data banks, accreditation, and consent rules—but was withdrawn in July 2023 after privacy critiques (e.g., familial searching risks, consent limits). In the absence of a dedicated statute, courts will lean on BSA/BNSS, constitutional privacy, and best-practice standards for admissibility and use.
