Use of Forensic Evidence in Criminal Trials: Admissibility and Reliability

Author: Sakshi Tripathi, United University, Prayagraj

To the Point

However, its admissibility hinges on scientific validity, procedural fairness, and judicial discretion. The Indian judiciary has gradually evolved standards to assess the reliability of such evidence under the Indian Evidence Act, 1872, ensuring that scientific truth aligns with legal truth.

Abstract

The use of forensic evidence in criminal trials has fundamentally transformed the landscape of criminal justice in India. With advancements in scientific techniques such as DNA profiling, fingerprint analysis, ballistics, digital forensics, and toxicology, forensic evidence has become a pivotal tool for investigators and prosecutors. However, the admissibility and reliability of such evidence continue to raise critical legal and constitutional questions.
This article delves into the complex intersection between science and law by examining how forensic evidence is introduced, evaluated, and weighed in the Indian criminal justice system. It discusses the statutory framework under the Indian Evidence Act, 1872—particularly Sections 45, 46, and 65B—and procedural provisions under the Criminal Procedure Code, 1973, that regulate the admissibility of expert opinions and scientific reports. The article analyzes judicial attitudes towards forensic evidence, highlighting that while courts recognize its potential to establish guilt or innocence.
Landmark judgments—including Selvi v. State of Karnataka, Mukesh v. State (NCT of Delhi), and Manu Sharma v. State (NCT of Delhi)—the article illustrates how courts have developed standards for evaluating forensic evidence, including the necessity of a continuous chain of custody, authentication of electronic records, and adherence to constitutional protections such as the right to fair trial and protection against self-incrimination.
Furthermore, the abstract explores the broader implications of over-reliance on forensic methods in a legal system grappling with infrastructural deficits, limited scientific expertise, and the risk of judicial bias towards seemingly objective science. It emphasizes that forensic evidence, while powerful, is not infallible and must be treated with caution and corroborated with other evidentiary materials. The article calls for robust institutional frameworks, improved forensic infrastructure, judicial training, and updated legislative guidelines to ensure the integrity of such evidence in court proceedings.
In essence, this article argues for a balanced approach: one that encourages the integration of science in criminal adjudication without compromising the foundational principles of criminal law—presumption of innocence, burden of proof, and procedural fairness. Only through such a careful calibration can forensic evidence truly serve the cause of justice without becoming a tool for unjust conviction.

Use of Legal Jargon

 Admissibility: Legal acceptability of evidence in a court of law.
 Expert Opinion (Section 45, Indian Evidence Act): Opinion given by a person special skilled in science or art.
 Corroborative Evidence: Supporting evidence that strengthens or confirms initial evidence.
 Circumstantial Evidence: Indirect evidence implying a fact.
 Presumption of Innocence: Legal principle that one is considered innocent until proven guilty.


The Proof

The relevance of forensic evidence is primarily governed by the Indian Evidence Act, 1872, especially:
Section 45 – Opinions of experts
Section 46 – Facts supporting expert opinion
Section 65B – Admissibility of electronic records
Section 293 CrPC – Reports of government scientific experts
Indian courts have both upheld and rejected forensic evidence depending on chain of custody, expert qualification, and consistency with other facts.

Case Laws

1. State of Maharashtra v. Praful Desai, (2003) 4 SCC 601
Held that electronic evidence like video conferencing is admissible. Expanded the meaning of “presence” in Section 273 CrPC.
2. Selvi v. State of Karnataka, (2010) 7 SCC 263
Held that narco-analysis, brain mapping, and polygraph tests conducted without consent violate Article 20(3) of the Constitution (right against self-incrimination).
3. Mukesh & Anr. v. State for NCT of Delhi (Nirbhaya Case), (2017)
Upheld the role of forensic DNA profiling and electronic evidence as vital corroborative tools, reinforcing their admissibility.
4. State of Uttar Pradesh v. Rajesh Gautam, (2003) 3 SCC 339
Reiterated that scientific evidence must be corroborated by other material evidence. Courts must avoid sole reliance on forensics if other evidence is weak.
5. Manu Sharma v. State (NCT of Delhi), (2010)
Stressed the need for complete and unbroken chain of custody to validate forensic reports like ballistic and blood tests.

Conclusion

In contemporary jurisprudence, forensic evidence represents a fusion of science and law—a potent tool for truth-finding. From DNA analysis to electronic surveillance, forensic methods offer the potential to convict the guilty and exonerate the innocent. However, with great power comes great responsibility.
On one hand, they acknowledge its efficacy in modern investigation; on the other, they remain wary of unverified or improperly handled forensic inputs. This balance is vital to prevent miscarriages of justice, especially in a system where investigation agencies often lack uniform protocols or sufficient infrastructure.
One of the key determinants of admissibility is Section 45 of the Indian Evidence Act, which allows expert opinions in matters of science, handwriting, fingerprinting, and digital data. However, such opinions are not conclusive and require corroboration. The Supreme Court has repeatedly emphasized that expert evidence is advisory, not binding on the court, as seen in State of HP v. Jai Lal.
If the evidence has passed through multiple hands, each transfer must be documented to ensure that it hasn’t been tampered with. Failure to maintain this chain could render the evidence inadmissible, as seen in the Manu Sharma case.
Another critical issue is technological competence. Courts must assess whether forensic labs follow internationally accepted protocols. Poorly trained technicians, outdated equipment, or vague reports can compromise the outcome of trials. In this context, judicial training on forensic science and better laboratory infrastructure is imperative.
Moreover, constitutional safeguards must never be bypassed. The Selvi case reiterates the principle that individual rights cannot be compromised in the name of scientific progress. Even the most accurate scientific tool cannot override the rights guaranteed under Articles 20 and 21 of the Constitution.
With cybercrime on the rise, courts must constantly adapt to innovations like blockchain, deepfakes, and encrypted data. The admissibility of such evidence under Section 65B has seen evolving interpretations, particularly after Anvar P.V. v. P.K. Basheer.
In conclusion, forensic evidence is a double-edged sword. It is neither infallible nor irrelevant. Courts must act as vigilant gatekeepers, ensuring that only scientifically valid, properly handled, and constitutionally sound forensic evidence enters the courtroom. The future lies not in blind faith in science, but in a judicious blending of technology with legal safeguards to uphold justice

FAQS

Q1. What is forensic evidence, and how is it different from other forms of evidence in criminal trials?
Ans:
Forensic evidence refers to information obtained through scientific methods to establish facts in legal proceedings. Unlike direct evidence (like eyewitness testimony) or documentary evidence, forensic evidence is derived from analysis in fields like biology, chemistry, physics, and technology. Examples include DNA testing, blood analysis, ballistics, fingerprints, digital footprints, and toxicology reports. It is often used to corroborate or disprove the claims of parties in a criminal trial and is presented through expert testimony.

Q2. Can forensic evidence alone lead to a conviction?
Ans:
While forensic evidence can be compelling, Indian courts typically do not rely on it in isolation unless it is overwhelming and corroborated by other evidence. The Supreme Court in several cases (e.g., State of UP v. Rajesh Gautam) has cautioned against sole reliance on scientific reports. Forensic evidence is usually treated as corroborative, not conclusive, unless it directly links the accused to the crime beyond reasonable doubt.

Q3. Are narco-analysis, lie detector tests, and brain-mapping legally admissible in India?
Ans:
No, not if conducted without consent. In Selvi v. State of Karnataka (2010), the Supreme Court held that these techniques violate the right against self-incrimination under Article 20(3) of the Constitution. Any information obtained through such tests without the individual’s consent is inadmissible. Even with consent, the results are not considered conclusive and can only be used as leads for further investigation.

Q4. What are the requirements under Section 65B of the Indian Evidence Act for electronic evidence?
Ans:
For electronic records (like emails, CCTV footage, call data records) to be admissible:
They must be accompanied by a certificate under Section 65B(4) stating the method of creation and authenticity.
The certificate must be signed by a person occupying a responsible position in relation to the device or process.
Failure to produce this certificate generally renders the evidence inadmissible, as affirmed in Anvar P.V. v. P.K. Basheer (2014).

Q5. Can the court reject expert opinion in a criminal case?
Ans:
Yes. Courts are not bound to accept expert opinions blindly. As per legal principles, expert testimony is advisory in nature and must be evaluated in light of other available evidence. If it contradicts the weight of other credible evidence, the court may reject it. This was reiterated in State of HP v. Jai Lal (1999), where the court emphasized scrutiny of the expert’s qualifications, methodology, and findings.

Q6. What if forensic reports from government laboratories are delayed or inconclusive?
Ans:
Delays or inconclusive reports weaken the prosecution’s case but do not automatically result in acquittal. Courts will consider whether the delay was prejudicial to the accused. Under Section 293 CrPC, reports from government laboratories can be admitted without formal proof, but the court can summon the expert for clarification. Inconclusive or ambiguous findings often reduce the evidentiary weight of the forensic report.

Q7. Is DNA evidence infallible? Can it be challenged?
Ans:
While DNA evidence is considered one of the most reliable forms of forensic evidence, it is not infallible. Errors can occur in sample collection, storage, testing, or interpretation. Cross-contamination and human error are common challenges. Defense lawyers often question the credibility of the lab, the chain of custody, or the methods used. Courts require strict compliance with protocols and scientific standards to trust DNA results.

Q8. Can an accused be compelled to provide fingerprints, blood samples, or DNA? Does it violate Article 20(3)?
Ans:
No, it does not violate Article 20(3). The protection under Article 20(3) extends only to testimonial compulsion—not to physical evidence like fingerprints, handwriting, or blood samples. Courts, under the Identification of Prisoners Act, 1920 and Section 53 CrPC, can authorize such collection if necessary for investigation. However, these procedures must be conducted under proper legal oversight.

Q9. How do courts deal with contradictory forensic expert opinions?
Ans:
If opposing parties present conflicting expert reports, the court examines:
Qualifications and credibility of the experts
Scientific basis and clarity of the reports
Consistency with other evidence
The court may also appoint an independent expert or seek a third-party neutral analysis to resolve contradictions.

Q10. What are some real-life cases where forensic evidence played a decisive role?
Ans:
Nirbhaya Case (Mukesh v. State NCT of Delhi, 2017) – DNA evidence and electronic records were crucial for conviction.
Arushi Talwar Case – Heavily relied on forensic interpretation; but criticism arose over lab procedures and conflicting reports.
Ajmal Kasab Trial (2012) – Digital and ballistic forensics were pivotal in linking the accused to the 26/11 attacks.
Manu Sharma v. State (Jessica Lal murder case) – Forensic and ballistic reports strengthened circumstantial evidence.

Q11. Are Indian forensic labs up to global standards?
Ans:
Not entirely. Many Indian forensic science laboratories (FSLs) face challenges such as:
Lack of accreditation
Shortage of qualified personnel
Outdated equipment
Procedural lapses
These limitations can affect the quality and admissibility of forensic evidence. Experts have recommended the establishment of National Forensic Science Universities and standard operating procedures (SOPs) to improve standards.

Q12. How should lawyers handle forensic evidence during trials?
Ans:
Prosecution must ensure the evidence is properly collected, stored, and documented, with supporting certifications.
Defense should question chain of custody, expert qualifications, methodology, and consistency with other evidence.
Both sides may cross-examine the expert and may bring independent experts if needed.

Q13. Is there a need for forensic law reform in India?
Ans:
Yes. India requires:
A comprehensive Forensic Evidence Act
Mandatory accreditation of forensic labs
Regular training of investigators, lawyers, and judges in forensic science
Greater investment in forensic infrastructure and personnel
These reforms would ensure consistency, transparency, and fairness in the use of scientific evidence in courts.