DNA Evidence and the Law

 This week I’d like to introduce the book:

The Double Helix and the Law of Evidence / David H. Kaye.
Harvard University Press, 2010.
Location: Law Library KF9666.5 K39 2010

As the author, Mr. Kaye, characterizes in the Preface, the book is “part history, part legal analysis, part popular science, and part applied statistical analysis.”

The story begins in the 1930s when another type of evidence, “genetic markers” such as blood groups (ABO) or blood serum, was undergoing much the same kind of scrutiny and controversy as to its admissibility in the courts as would later confront modern DNA evidence.  At that time, the Frye standard was adopted and applied by the courts.  This standard allows that evidence be admissible if it the methodology has gained “general acceptance” within a relevant scientific community.  The trouble with this is there have been numerous dubious methods that have at one time or another been generally accepted and used by law enforcement to gather evidence.  Some of these methods that don’t really stand up to scientific scrutiny include voiceprints, bite-mark analysis, and lie detector tests.

Molecular biology came of age in the mid-1980s hand-in-hand with DNA typing and transformed the science of individual identification, as well as, the field of forensic science and the law of evidence.

In 1986-1988, during the first wave of court cases regarding the admissibility of DNA as evidence, the initial judicial response was uniformly positive.  The courts deciding that DNA evidence satisfied both the general acceptance and the ordinary relevance standards for admitting scientific evidence.  The first doubts about the reliability of DNA evidence began to surface in 1989-1990 where in one case the lab work analyzing the DNA in question was found to be so sloppy that the evidence was ruled inadmissable.  On another front, defense attorneys started pushing back with questions about statistical probabilities and population genetics.  Arguing the question “What if the DNA sample under scrutiny actually matched someone else other than the suspect?”

The FBI by then had started work in both areas: developing standards for labs handling DNA samples and sounder statistical models.  Likewise, the National Research Council (NRC) initiated a sweeping review of forensic DNA technology in 1989 with its first report issued in 1992.  The New York Times published a front-page article with the flaming headline “U.S. Panel Seeking Restriction on Use of DNA in Courts.”  The Times got the story wrong, though, the report said no such thing.

A good portion of the book thereafter is devoted to the O.J. Simpson trial of 1995.  O.J.’s “Dream Team” had initially filed a “Motion to Exclude DNA Evidence.”  Shortly before the trial was to begin, the defense filed notice withdrawing their objections to the admissibility of the DNA evidence.  The notice, however, reserved the right “to challenge the weight and reliability of the prosecution’s scientific evidence at trial, including...the scientific reliability of DNA testing and statistical techniques...and the performance of law enforcement authorities and forensic laboratories in their handling of the samples and evidence in this case and in their slipshod execution of these techniques.”

Despite all the reservations made during the O.J. trial, the author suggests that “the televised presentations on forensic DNA technology enhanced the belief of the general public - and many trial and appellate judges - that the technology was ready for prime time.”  A second NRC Report issued in 1996 also seemed to settle the waters citing a growing body of published scientific research validating the methods and technology securing DNA evidence.

Throughout it all, judicial acceptance came incrementally as the battles over admissibility went state-by-state, jurisdiction-by-jurisdiction.  At the federal level, Daubert (1993) was something of a watershed setting a stricter “scientific-validity standard” than found in the Frye “general acceptance” standard.  The “Daubert triology” as set forth in Rule 702 of the Federal Rules of Evidence requires:

    1) the testimony is based upon sufficient facts or data,
    2) the testimony is the product of reliable principles and methods, and
    3) the witness has applied the principles and methods reliably to the facts of the case.

As the law has settled over time, 2007 marked the year the 200th convict was exonerated by DNA testing in the United States.  Some of those have our own Wisconsin Innocence Project at the U.W. Law School to thank for their newfound freedom.


Submitted by Eric Taylor, Evening Reference Librarian on February 24, 2011

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