St. Mary's Law Journal


Throughout legal history, courts have wrestled with scientific evidence. Sometimes the courts admitted invalid evidence disguised as science. In the 1920’s, courts developed a very limited standard of admissibility for scientific evidence. Under the Frye test, a scientific expert’s conclusion was inadmissible unless the conclusion was generally accepted by the scientific community. Although this prevented “junk science” from invading courtrooms, it also protected invalid scientific evidence already present in the system and restricted using new, but valid, scientific techniques. In response, many jurisdictions developed more liberal evidentiary standards. The liberal standards averted the “cultural lag” for which Frye was criticized but exposed the courtroom to a host of flawed scientific conclusions. Because of its unique nature, scientific information creates significant evidentiary pitfalls. To avert these problems, lawyers and judges must realize scientific evidence has two components: validity and reliability. To properly determine admissibility, the judicial system must assess scientific evidence by reviewing both components. The judge should review the methodology or reasoning which led to the scientific expert’s conclusion. If the expert applied a methodology or reasoning commonly applied by the expert’s peers, the scientific conclusion is valid. With validity determined, the trier of fact can play its customary role of assessing the reliability of the evidence. However, the trier of fact faces another of scientific evidence’s pitfalls. Laypersons often view science differently than scientists. To effectively avoid the pitfalls of scientific evidence, the court must transform the trier of fact from scientific traditionalists to scientific modernists. Initially, using scientific evidence effectively will be an onerous task. However, by applying the two-step approach of analyzing validity and reliability of evidence and by educating the trier of fact, the legal system can be healed of the evidentiary disease and inoculated against future infection.


St. Mary's University School of Law