The use of dna evidence

We begin with a discussion of the investigation stage, but devote most of our attention to admissibility. In that context, we review some of the rapidly growing number of cases involving admissibility.

The use of dna evidence

We begin with a discussion of the investigation stage, but devote most of our attention to admissibility.

How DNA Evidence Works - FindLaw

In that context, we review some of the rapidly growing number of cases involving admissibility. Discussion of case law is intended mainly to highlight specific issues and is not intended to be comprehensive. Finally, we make a series of practical recommendations, with judges especially in mind.

To produce biological evidence that is admissible in court in criminal cases, forensic investigators must be well trained in the collection and handling of biological samples for DNA analysis.

They should take care to minimize the risk of contamination and ensure that possible sources of DNA are well preserved and properly identified. As in any forensic work, they must attend to the essentials of preserving specimens, labeling, and the chain of custody and to any constitutional or statutory requirements that regulate the collection and handling of samples.

The Fourth Amendment provides much of the legal framework for the gathering of DNA samples from suspects or private places, and court orders are sometimes needed in this connection.

Wherever possible, a preserved sample should be large enough to enable the defense to obtain an independent RFLP analysis, but there should Page Share Cite Suggested Citation: The National Academies Press.

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All materials relied on by prosecution experts must be available to defense experts, and vice versa. The laboratories used for analysis must be reliable and should be willing to meet recognized standards of disclosure.

In civil noncriminal cases—such as paternity, custody, and proof-of-death cases—the standards for admissibility must also be high, because DNA evidence might be dispositive. The relevant federal rulesand most state rules of evidence do not distinguish between civil and criminal cases in determining the admissibility of scientific data.

In a civil case, however, if the results of a DNA analysis are not conclusive, it will usually be possible to obtain new samples for study. As in criminal cases, laboratories and other interested parties must treat evidence according to established protocols. The advent of DNA typing technology raises two key issues for judges: A host of subsidiary questions with respect to how expert evidence should be handled before and during a trial to ensure prompt and effective adjudication apply to all evidence and all experts and are not dealt with in this chapter.

One is the Frye test, enunciated in Frye v. In addition, several states have recently enacted laws that essentially mandate the admission of DNA typing evidence.

The Frye Test The test for the admissibility of novel scientific evidence enunciated in Frye v. United States has been the most frequently invoked one in American case law. A majority of states profess adherence to the Frye rule, although a growing number have adopted variations on the helpfulness standard suggested by the Federal Rules of Evidence.

Admissibility

Frye predicates the admissibility of novel scientific evidence on its general acceptance in a particular scientific field: In practice, the court is much more involved. The court must determine which scientific fields experts should be drawn from.

The use of dna evidence

Complexities arise with DNA typing, because the full typing process rests on theories and findings that pertain to various scientific fields. For example, the underlying theory of detecting polymorphisms is accepted by human geneticists and molecular biologists, but population geneticists and statisticians might differ as to the appropriate method for determining the population frequency of a genotype in the general population or in a particular geographic, ethnic, or other group.

When a process is new and complex, a court should recognize that the expertise of more than one discipline might be necessary to explain it. That is the case when the admissibility of DNA evidence is judged as a matter of first impression.

Assumption 2—concerns the validity of procedures for extracting DNA from samples of blood, semen, and other materials and analyzing it for the presence and size of polymorphisms. With regard to application in scientific research, the validity is sufficiently well established in the case of RFLP analysis with Southern blots that judicial notice is also appropriate.

With regard to the application in forensic science, however, additional questions Page Share Cite Suggested Citation: For example, forensic DNA analysis frequently involves the use of small, possibly contaminated samples of unknown origin, such as a dried blood stain on a piece of clothing.

Some experts have questioned the reliability of DNA analysis of samples subjected to "crime scene" conditions. In addition as noted in Chapters 2 and 3the details of the particular techniques used to perform DNA typing and to resolve ambiguities evoke a host of methodological questions.

It is usually appropriate to evaluate these matters case by case in accordance with the standards and cautions contained in earlier portions of this report, rather than generally excluding DNA evidence. Of particular importance once such a system of quality assurance is established would be a demonstration that the involved laboratory is appropriately accredited and its personnel certified.

Some aspects such as the validity of the theory underlying RFLP analysis might be so well established that judicial notice is warranted. Others such as quantitative correction of band shifting with a single monomorphic fragment might not be sufficiently well established to justify admissibility.

Assumption 3—related to the adequacy of statistical databanks used to calculate match probabilities—rests on unproven foundations.In recent years, legislative issues have become the focus, stemming from the increased use of DNA databanking and the movement to allow post-conviction DNA testing.

Evolution of DNA Evidence for Crime Solving - A Judicial and Legislative History. But catching a criminal using DNA evidence is not quite as easy as "CSI" makes it seem, as this article will demonstrate. Our first step in exploring DNA evidence is the crime scene -- and the biological evidence gathered there by detectives.

DNA profiling is a forensic technique in criminal investigations, comparing criminal suspects' profiles to DNA evidence so as to assess the likelihood of their involvement in the crime. It is also used in parentage testing, [2] to establish immigration eligibility, [3] and in genealogical and medical research.

6 Use of DNA Information in the Legal System This chapter provides an overview of how DNA evidence might be used in the investigation and prosecution of crimes and in civil litigation. The DNA typing discussed in this chapter is mainly standard single-locus RFLP typing on Southern blots without apparent band shifting; i.e., it is the technique most often considered by the courts to date.

6 Use of DNA Information in the Legal System This chapter provides an overview of how DNA evidence might be used in the investigation and prosecution of crimes and in civil litigation.

The DNA typing discussed in this chapter is mainly standard single-locus RFLP typing on Southern blots without apparent band shifting; i.e., it is the technique.

Aug 23,  · Commentary and archival information about DNA Evidence from The New York Times. the latest in the Manhattan district attorney’s effort to use DNA to crack cold cases.

DNA Evidence legal definition of DNA Evidence