DNA Technology in Law and Public Policy
The technologies of DNA science have revolutionized modern criminal law in every respect, from crime scene processing and case investigation to prosecutorial strategy and post-conviction appeals. The lightning speed of progress in the DNA sciences represents a public policy challenge to optimize its evidentiary value without violating established principles of constitutional protections, criminal procedure and statutory rules of evidence. Ultimately, projected developments in DNA science and technology will affect ordinary life far beyond the realm of the criminal justice system by eliminating genetic diseases and providing a cure (or preventative) for all forms of cancer as well.
Background and History:
Throughout the eighteenth century, medical science was still entirely ignorant of the reason that human blood transfusions succeeded sometimes, but failed other times, with deadly consequences. By the turn of the twentieth century, scientists realized that human blood could be differentiated by four types, by analyzing the coagulation or "clumping" that resulted when some blood samples were mixed together in the laboratory. Continued research into the antigens responsible for different hemoglobin characteristics lead to the standardized blood group designations that are still employed today, and upon which all subsequent medical and surgical progress and techniques requiring transfusions or organ transplants depend.(1)
It was realized almost immediately, that blood typing had potential value for criminal identification investigations, paternity confirmation and exclusion, and other evidentiary purposes, because they were dictated by Mendel's Laws of Inheritance.
By the 1960s', researchers had identified many other more subtle factors than surface antigens, enabling them to differentiate blood samples by virtue of specific enzymes and serum proteins that conferred much greater accuracy to the determinations (or exclusions) of identity revealed through blood studies.
Initially, evidence relating to identity and paternity primarily sought to exclude potential candidates from further consideration or exonerate criminal suspects, rather than to include candidates or inculpate suspects, owing to the factor of mathematical error inherent in blood testing principles relying on the parameters capable of analysis. Similarly, when first admitted into evidence in courts of law, identification by blood evidence was first accepted in civil matters, where the standard of proof is preponderance, and much more rarely in criminal matters, where stricter thresholds of proof precluded its use, in principle. (2)
In 1953, decades of research by many scientists in the United States and Europe culminated in the monumental discovery and publication of the actual structure of the DNA molecular helix by Watson and Crick, for which they received the Nobel Prize in 1962. Continued research over the next two decades yielded a much deeper scientific understanding of the role of DNA and produced incredibly precise technologies based on more sophisticated principles governing recombinant
DNA processes.
1985 marks a watershed in the history of forensic science, when so-called variable-length DNA segments were used in England to exonerate an innocent man of rape charges and to conclusively establish the guilt of the actual perpetrator.(3)
Since that time, the reliability and demonstrable accuracy of DNA evidence has been established and confirmed conclusively, and is not contested, in principle, in court.
On the other hand, the technological sophistication of modern DNA sequencing techniques have given rise to a plethora of public policy debates about the privacy of medical records, precisely because of the wealth of diagnostic and particularly, prognostic information contained therein. Constitutional issues arise in connection with 4th Amendment search and seizure of biological criminal evidence, requiring a legal definition of the "privacy" expectations of medical information and establishing "ownership" of biological samples and patent applications for genetically engineered organisms.(4)
Modern Law Enforcement Applications:
When fingerprinting was first used for identification purposes in 1892, it revolutionized criminal investigations, forming the cornerstone of countless successful investigations, prosecutions and convictions in every imaginable area of law enforcement. Suddenly, criminals could be tied directly to their crimes and authorities simultaneously acquired an invaluable tool for reliably cataloging and cross-referencing career criminals. The explosive evolution of DNA science since
1985 advanced criminal investigations and forensic science by a much greater magnitude than even the finger print revolution of one hundred years ago.
DNA-based techniques reveal evidentiary clues in such a wide variety, that a clean" crime scene is quite rare. Positive identification beyond the shadow of doubt can be gleaned from a single human hair, a drop of blood or perspiration, a saliva stains on cigarette butts and postage stamps, or a microscopic particle of skin or dandruff. It has enabled law enforcement to establish "CODIS" (for Combined DNA
Index System), a nationwide DNA data bank and identification system modeled in principle,...
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