Case Law On Forensic Evidence And Dna Profiling
orensic Evidence and DNA Profiling: Detailed Explanation
Forensic evidence refers to scientific evidence obtained through various techniques such as fingerprint analysis, ballistic reports, toxicology, and especially DNA profiling. DNA profiling has revolutionized criminal justice by providing a highly accurate method to identify or exclude suspects based on biological samples.
Key aspects of forensic and DNA evidence:
Reliability and Accuracy: DNA evidence is considered highly reliable, but only when collected, preserved, and analyzed properly.
Chain of Custody: Maintaining the integrity of samples from collection to presentation in court is essential.
Expert Testimony: Courts rely on forensic experts to explain the findings in an understandable way.
Legal Standards: Courts require proof that the forensic procedures followed scientific standards and the results are relevant and not prejudicial.
Important Case Laws on Forensic Evidence and DNA Profiling:
1. State of Punjab v. Gurmit Singh (1996) – India
Summary: This was one of the first Indian Supreme Court cases that recognized DNA profiling as admissible evidence. The Court laid down guidelines ensuring the reliability and scientific validity of DNA tests.
Principle: DNA evidence is admissible if conducted by accredited labs using accepted scientific methods and the results are corroborated with other evidence.
Impact: Established DNA profiling as a strong tool in criminal trials, but with safeguards to prevent misuse.
2. People v. Castro (1989) – USA
Summary: The New York Court of Appeals cautioned about over-reliance on DNA evidence and stressed that DNA evidence must be evaluated in the context of all evidence.
Principle: DNA evidence alone is not conclusive; the court must consider potential errors, laboratory procedures, and other case facts.
Impact: Emphasized the necessity of corroborating DNA evidence with other evidence and scrutinizing forensic procedures.
3. R v. Doheny and Adams (1997) – United Kingdom
Summary: The English Court of Appeal discussed the interpretation of DNA evidence probabilities. The court ruled that DNA evidence must be presented with clear statistical interpretation to avoid misleading the jury.
Principle: Forensic experts must explain DNA match probabilities clearly, and courts must guard against the “prosecutor’s fallacy.”
Impact: Improved the communication and understanding of DNA statistical evidence in courts.
4. Kumari Shrilekha Vidyarthi v. State of U.P. (1991) – India
Summary: The Supreme Court discussed the role of scientific evidence, including DNA, emphasizing it should be supplementary to other evidence and not the sole basis for conviction.
Principle: Scientific evidence strengthens prosecution but cannot replace the need for a comprehensive evaluation of facts.
Impact: Reinforced that DNA and forensic evidence must be considered as part of the entire evidentiary framework.
5. Melendez-Diaz v. Massachusetts (2009) – USA
Summary: The U.S. Supreme Court ruled that forensic lab reports used as evidence must comply with the defendant’s Sixth Amendment right to confront witnesses. The analysts who performed tests must testify or be available for cross-examination.
Principle: Defendants have the right to cross-examine forensic experts whose reports are used against them.
Impact: Strengthened procedural safeguards ensuring forensic evidence is subject to adversarial testing.
Summary of Legal Principles from These Cases:
Admissibility of DNA evidence requires scientific validity and procedural safeguards (Gurmit Singh).
DNA evidence is not infallible and must be corroborated (People v. Castro).
Courts must be careful about statistical interpretation of DNA matches (Doheny and Adams).
Forensic evidence supplements but does not replace comprehensive proof (Kumari Shrilekha).
Right to confront and cross-examine forensic experts is fundamental (Melendez-Diaz).
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