The Uses and Effects of Forensic Science in the Adjudication of Felony Cases

This paper describes the uses and effects of forensic and other forms of evidence on the judicial processing of criminal cases. To achieve this goal, several data gathering approaches were used: surveys of laboratory scientists, interviews with prosecutors and defense attorneys, issuance of hypothetical case scenarios to prosecuting attorneys, exit surveys of citizens discharged from jury service, and a review of several thousand randomly chosen felony case filings in five prosecutors' offices. Aside from drug and alcohol related cases, firearms, bloodstains, fingerprints, hair, and semen are the leading categories of scientific evidence examined in felony prosecutions. Taking into account a variety of other sociodemographic and evidentiary factors, the authors find that scientific evidence makes little difference in prosecutors' decisions to charge defendants, or for that matter in the determination of guilt or innocence of charged defendants. Confessions emerge as the principal form of evidence influencing decisions to convict or acquit defendants. Forensic science reports and testimony have their greatest impact at the time of sentencing, when convicted defendants are more likely to go to prison and for longer periods of time where scientific evidence is presented.