Evaluation of Forensic DNA Evidence

• NCJ Number: 166538
• Date Published: 1996
• Length: 244 pages
• Grant Number(s): 93-IJ-CX-0008
• Agencies: NIJ-Sponsored
• Publication Type: Program/Project Evaluation

Annotation

This report describes both the science behind DNA profiling and the data on the frequency of profiles in human populations; it recommends procedures for providing various statistics that may be useful in the courtroom.

Abstract

The first chapter describes the 1992 report, the changes since that report, the uses and validity of DNA typing, differences between DNA typing in criminal cases and in civil paternity litigation, reasons for the seemingly contradictory probability estimates that various experts sometimes present in court, and the committee's approach to the issue of "population structure." Chapter 2 describes the genetic and molecular basis of DNA typing, followed by a chapter on laboratory performance. The latter chapter includes descriptions of ways that errors can arise and how their occurrence might be minimized. It contains recommendations on quality control and assurance, laboratory accreditation, proficiency tests, and confirmatory testing. Chapter 4 explains the generally applicable principles of population genetics and then considers the implications of the fact that the population of the United States contains various groups and subgroups with different mixes of genes. The fifth chapter considers how the estimated frequency of an incriminating DNA profile relates to conclusions about the source of the DNA in the evidence sample. It concludes that the abundance of data in various ethnic groups within the major races and the methods outlined in the previous two chapters imply that the 1992 report's suggested ceiling principle and interim ceiling principle are unnecessary. The final chapter discusses the legal implications of the conclusions and recommendations. 233 references