The Role and Impact of Forensic Evidence on the Criminal Justice Process

This proposal describes a unique and comprehensive approach for determining the role and impact of forensic evidence in the processing of criminal cases. The study will include a prospective analysis of official record data that follows criminal cases in four jurisdictions (Los Angeles County, Indianapolis-Marion County, Springfield-Hampden County, MA, and a site TBD in Florida) from the time of police incident report to final criminal disposition. A total of 1,000 cases per site will be drawn from the population of serious crimes reported to the police, stratified by crime type (e.g., homicides, attempt murder/aggravated assaults, sexual assaults, robberies, and burglaries), for the year 2003. Because of case attrition, additional case sampling will occur at the arrest and charging stages. Samples will also be supplemented, at the laboratory level, to insure a minimum of 500 crime laboratory case files (stratified by crime type) where physical evidence is examined and reports are filed.

The study will track the evidence from the crime scene into the evidence bases property room, onto the analyst's bench, through its examination and interpretation, and report to interested parties. The laboratory's exploitation of fingerprint, DNA, and firearms data will be documented. The quality of the scientific evidence and its ability to answer key questions with respect to the alleged criminal incident and persons responsible will be explored. The study will explore the effect of forensic evidence on seven different case outcomes, from a reported crime incident and arrest to sentence outcomes. The study will include a variety of individual-and contextual-level independent variables and will use hierarchical linear modeling (HLM) procedures to assess the impact of forensic evidence on case outcomes.

In addition to these analyses, project staff will complete a series of 'mini-studies' that probe in greater depth key evidence processing matters that this type of study needs to answer: factors that explain why crime scene investigations often do not result in productive physical evidence; how innovative labs may limit the huge share of resources devoted to drug identification cases; the central and increasing role being played by DNA typing in solving personal and property crimes; how scientific evidence may affect the time and resources to resolve routine criminal investigations; how greater use of scientific evidence by the defense influences case outcome; the role played by scientific evidence in plea negotiations, and how forensic evidence is being viewed by lay and legal fact-finders at the judicial level. CA/NCF