Chapter 1: Forensic Science Overview
Forensic Laboratory Development in the United States
Rapid growth with a lack of national and regional planning/cooperation.
4 major reasons for the increase since the 1960s:
The requirement to advise criminal suspects of constitutional rights and right to counsel reduced confessions as a routine investigative tool.
Staggering increase in U.S. crime rates.
All illicit-drug seizures must be sent to a forensic laboratory for confirmatory chemical analysis before adjudication.
Advent of DNA profiling.
5 basic services provided by crime laboratories:
Physical science unit
Biology unit
Firearms unit
Document examination unit
Photography unit
Optional services some labs offer: toxicology, fingerprint analysis, polygraph administration, voiceprint analysis, and crime-scene investigation.
Special forensic science services available to law enforcement: forensic pathology, forensic anthropology, forensic entomology, forensic psychiatry, forensic odontology, forensic engineering, and forensic computer/digital analysis.
Functions of the Forensic Scientist
Primarily relies on scientific knowledge/skill; half the job done in the laboratory, half in the courtroom.
Must analyze physical evidence and persuade a jury to accept conclusions drawn from that analysis.
Analyzing Physical Evidence
Physical evidence is free of inherent error or bias in comparison to confessions or eyewitness accounts.
Investigators rely on physical evidence because it must undergo scientific inquiry; integrity comes from adherence to the scientific method.
Scientific method essentials:
Formulate a question worthy of investigation (e.g., who committed the crime).
Propose a hypothesis.
Test the hypothesis through experimentation.
Results must be thorough and accepted by other scientists.
If validated, the hypothesis becomes suitable scientific evidence for use in investigation and court.
Admissibility of evidence – Frye standard (1923): evidence is admissible if the questioned procedure/technique is "generally accepted" by a meaningful segment of the relevant scientific community.
Frye approach often requires experts to testify that the issue is generally accepted; consideration of literature and prior judicial decisions.
Federal Rules of Evidence offer a more flexible alternative: Rule allows expert testimony if the witness is qualified by knowledge, skill, experience, training, or education, and the testimony:
Is based on sufficient facts or data,
Derives from reliable principles and methods,
Applies the principles/methods reliably to the facts of the case.
Daubert v. Merrell Dow Pharmaceuticals, Inc. (): general acceptance is not an absolute prerequisite for admissibility; the trial judge acts as a gatekeeper under the Rules of Evidence. The Trial Judge has responsibility
The interplay between Frye, Daubert, and Rule shapes how scientific evidence is evaluated in court.
The Scientific Method (definition)
A process that uses strict guidelines to ensure careful and systematic collection, organization, and analysis of information.
Serves as a safety net to prevent outcomes from being tainted by human emotion or biased by contrary evidence.
Voir Dire
“a preliminary examination of a witness or a juror by a judge or counsel”