Dna Evidence Admissibility
What is DNA Evidence Admissibility?
DNA evidence is genetic material used to link a suspect to a crime scene or victim. Its admissibility depends on courts being confident about the evidence’s reliability, relevance, and proper collection/handling.
Landmark Cases on DNA Evidence Admissibility
1. Frye v. United States (1923)
Issue: Early standard for admitting scientific evidence.
Facts: Polygraph test admitted as evidence; defense argued it was unreliable.
Holding: Court established the "general acceptance" test — scientific evidence must be generally accepted by experts in the field to be admissible.
Significance: Set the first important standard, later applied to DNA evidence, requiring scientific consensus.
2. Daubert v. Merrell Dow Pharmaceuticals (1993)
Issue: Clarified the standard for admitting expert scientific testimony, including DNA evidence.
Facts: Plaintiff challenged admission of expert testimony about drug risks.
Holding: The Supreme Court replaced the Frye test with a more flexible standard — judges act as “gatekeepers” to ensure reliability and relevance based on factors like testability, peer review, error rates, and acceptance.
Significance: Daubert became the main test for DNA evidence admissibility in federal and many state courts.
3. People v. Castro (1989, New York Court of Appeals)
Issue: Whether DNA evidence was sufficiently reliable and properly interpreted.
Facts: The defendant argued that DNA evidence used in his conviction was flawed.
Holding: The court excluded DNA evidence because the methods and statistical calculations were not sufficiently standardized.
Significance: Emphasized rigorous scientific methods and statistics must back DNA evidence for admissibility.
4. United States v. Jakobetz (1997)
Issue: The application of Daubert to DNA testing methods.
Facts: Defendant challenged the admissibility of DNA evidence obtained through PCR (polymerase chain reaction) techniques.
Holding: The court admitted the evidence, ruling that PCR met the Daubert criteria (peer review, error rates, general acceptance).
Significance: Affirmed newer DNA techniques can be admissible if properly validated.
5. Coppolino v. State (1968, Florida Supreme Court)
Issue: Admissibility of new scientific techniques in evidence.
Facts: Involved a new chemical test for poison; while not DNA, it set precedent.
Holding: Court ruled that scientific evidence must be evaluated on reliability, not just acceptance.
Significance: Helped pave the way for later DNA evidence acceptance under Daubert.
6. Maryland v. King (2013)
Issue: Whether collecting DNA from arrestees violates the Fourth Amendment.
Facts: Maryland law allowed DNA swabs upon arrest; King challenged it as unlawful search.
Holding: Supreme Court ruled DNA collection is a legitimate booking procedure, akin to fingerprinting.
Significance: Supports widespread DNA databases and expanded DNA evidence use.
7. People v. Williams (1997, California)
Issue: Admissibility and weight of DNA evidence in court.
Facts: Defendant argued DNA evidence was mishandled.
Holding: Court emphasized strict chain of custody and laboratory protocols for admissibility.
Significance: Reinforces procedural safeguards to ensure DNA evidence integrity.
Summary Table
| Case | Key Issue | Outcome/Significance |
|---|---|---|
| Frye v. United States | General acceptance of scientific evidence | Established early “general acceptance” standard |
| Daubert v. Merrell Dow | Judge as gatekeeper of scientific testimony | Created flexible reliability standard for DNA evidence |
| People v. Castro | Reliability and interpretation of DNA evidence | Excluded DNA for lack of standardized methods |
| United States v. Jakobetz | Admissibility of PCR DNA methods | Admitted DNA based on Daubert criteria |
| Coppolino v. State | Reliability over acceptance in new science | Set groundwork for modern scientific evidence evaluation |
| Maryland v. King | DNA collection from arrestees and 4th Amendment | DNA collection upheld as legitimate booking procedure |
| People v. Williams | Handling and chain of custody of DNA evidence | Stressed procedural safeguards for admissibility |
Key Takeaways:
Courts require DNA evidence to be scientifically valid, reliable, and relevant.
The Daubert standard is the modern test: judges ensure evidence is backed by sound science.
Proper collection, preservation, and lab procedures are essential to avoid challenges.
DNA evidence can raise constitutional questions, but courts generally allow it if handled properly.
Landmark cases often balance scientific advances with legal safeguards to protect defendants’ rights.
RELATED Blog
0 comments