DNA: Forensic and Legal Applications.
No subject is as conceptually complex, operationally technical, and professionally necessary to understand today than deoxyribonucleic acid (DNA). It has radically changed the way the criminal justice system works; its collection and analysis leads to convictions of previously unknown criminals and to the exoneration of the innocent accused. Almost every criminal law practitioner can testify to the impact of the DNA revolution, especially to the expectations of jurors and other laypersons on what the effects of forensic science should be in solving criminal cases, partly because of glamorization by the plethora of forensic investigation programs on television. Therefore, prosecutors should understand the science of DNA analysis as thoroughly as possible to counter objections from the defense and to begin to meet or forestall the expectations of jurors.
An appropriate beginning text for this purpose is DNA: Forensic and Legal Applications. The authors approach the subject starting from the most basic understanding of the scientific background of DNA analysis and expanding to the actual methodology used in the various testing processes. They also discuss general principles of forensic science and data collection/crime scene investigation, including the strengths and weaknesses of each of the currently used DNA analyses. Particularly helpful is the insight gained from viewing each process on a theoretical and conceptual basis (i.e., understanding what is being tested and compared in each testing method), rather than just reading a lab report where a technician used a certain method that provided a particular result. Indeed, knowing the strengths and limitations of each technique can explain why others were not used, as well as to better point out the valuable information gained by using one process, rather than another.
Prosecutors, in particular, may want to pay close attention to the authors' emphasis on the importance of statistical matters and population genetics in DNA analysis. DNA evidence, for example, can show that the sample collected from a rape victim cannot be excluded as having come from a defendant or suspect because to get a random match as tested would occur only once in billions or trillions of tests. Thorough comprehension of the ideas that make DNA evidence so remarkably probative in court will prepare counsel to present the material to the jury in an understandable and persuasive way. In addition, the sections dealing with mixed samples (containing multiple sources of DNA) and the methods used to manage such results are helpful, especially in rape cases where mixed DNA samples may occur.
The authors expend some effort discussing the legal history of admitting DNA and other scientific or technical evidence, including the Frye and Daubert decisions and their progeny. This material is not only of historical value but of practical importance because the science of DNA testing continues to change and new methods of analysis eventually will have to pass one of these standards to be admissible in court.
Whole sections of the book contain discussions and exemplars of how to conduct voir dire, question experts, make objections, and close effectively in DNA cases. That much of this material is written from a defense perspective matters not at all for prosecutors because anticipating where their opposition might occur often proves as important as determining what strategy they will use to present their own cases.
Chapters dealing with scientific materials each contain a healthy reference bibliography for further study or collaboration with a DNA expert. The work closes with appendices detailing further bibliographical sources, state and federal court cases addressing the admissibility of various DNA testing methods, contact information for innocence projects, defense DNA discovery request suggestions, and a glossary.
DNA: Forensic and Legal Applications is a valuable resource for criminal practitioners, particularly prosecutors, in dealing with progressively more common and relied-upon DNA evidence. This fairly short text (364 pages, including bibliographic materials, appendices, and an index) will help them gain a more foundational and in-depth understanding of the mechanics of DNA testing and the theory behind it that gives meaning to the science and makes it so relevant in court, as well as provide them with the impetus for sparking ideas about how better to present a DNA case before judge and jury.
Robert E. Stephens, Jr.
Assistant Commonwealth's Attorney
34th Judicial Circuit