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The application of scientific knowledge and methodology to legal problems and criminal investigations.
Sometimes called simply forensics, forensic science encompasses many different fields of science, including anthropology, biology, chemistry, engineering, genetics, medicine, pathology, phonetics, psychiatry, and toxicology.
The related term criminalistics refers more specifically to the scientific collection and analysis of physical evidence in criminal cases. This includes the analysis of many kinds of materials, including blood, fibers, bullets, and fingerprints. Many law enforcement agencies operate crime labs that perform scientific studies of evidence. The largest of these labs is run by the Federal Bureau of Investigation.
Forensic scientists often present Expert Testimony to courts, as in the case of pathologists who testify on causes of death and engineers who testify on causes of damage from equipment failure, fires, or explosions.
Modern forensic science originated in the late nineteenth century, when European criminal investigators began to use fingerprinting and other identification techniques to solve crimes. As the field of science expanded in scope throughout the twentieth century, its application to legal issues became more and more common. Because nearly every area of science has a potential bearing on the law, the list of areas within forensic science is long.
Forensic Medicine and Psychology
Forensic medicine is one of the largest and most important areas of forensic science. Also called legal medicine or medical Jurisprudence, it applies medical knowledge to criminal and Civil Law. Areas of medicine that are commonly involved in forensic medicine are anatomy, pathology, and psychiatry.Many law enforcement agencies employ a forensic pathologist, sometimes called a medical examiner, who determines the causes of sudden or unexpected death. Forensic toxicologists, who study the presence of poisons or drugs in the deceased, often help forensic pathologists. Forensic odontologists, or dentists, analyze dental evidence to identify human remains and the origin of bite marks.
Forensic medicine is often used in civil cases. The cause of death or injury is considered in settling insurance claims or Medical Malpractice suits, and blood tests often contribute to a court's decision in cases attempting to determine the Paternity of a child.
Forensic Science in the Federal Bureau of Investigation
Since its establishment in 1932, the FBI Laboratory has been a world leader in the scientific analysis of physical evidence related to crime. From its location in the J. Edgar Hoover FBI Building, in Washington, D.C., the laboratory provides a wide range of free forensic services to U.S. law enforcement agencies. The laboratory is divided into several major departments: the Document Section, Scientific Analysis Section, Special Projects Section, Latent Fingerprint Section, and Forensic Science Research and Training Center.
The laboratory's Document Section examines paper documents, ink, shoe and tire tread designs, and other forms of evidence related to a wide variety of crimes, including forgery and Money Laundering. It performs linguistic analysis of documents to determine authorship. It also evaluates the validity and danger of written threats. Its Computer Analysis and Response Team recovers evidence, including encrypted information, from computer systems—evidence that is crucial to the prosecution of White-Collar Crime. The Document Section also maintains files of bank Robbery notes, anonymous Extortion letters, and office equipment specifications.
The Scientific Analysis Section has seven divisions: Chemistry Toxicology, DNA Analysis/Serology, Elemental and Metals Analysis, Explosives, Firearms-Toolmarks, Hairs and Fibers, and Materials Analysis. This section's analysis of blood, semen, and saliva assists the investigation of violent crimes such as murder, rape, assault, and hit-and-run driving. Its research also provides insight into many other crimes, including bombings, Arson, drug tampering, and poisoning.
The services provided by the Special Projects Section include composite sketches of suspects, crime scene drawings and maps, videotape and audiotape analysis and enhancement, and analysis of electronic devices such as wiretaps and listening devices.
The Latent Fingerprint Section examines evidence for hidden fingerprints, palm prints, footprints, and lip prints.
The Forensic Science Research and Training Center offers classes to law enforcement officials from the United States and other countries. These classes cover DNA analysis, the detection and recovery of human remains, arson and bomb blast investigation, and many other topics.
To better perform its research, the laboratory maintains files on many kinds of physical evidence, including adhesives, ammunition, paint, and office equipment. The laboratory also provides experts who will furnish testimony on the nature of the evidence.
The laboratory publishes the Handbook of Forensic Science to explain its forensic services to law enforcement agencies. The handbook outlines procedures for safely and effectively gathering evidence from crime scenes and shipping it to the laboratory for analysis.
Mental health and psychology professionals have contributed a great deal to the legal understanding of issues such as the reliability of Eyewitness testimony, responsibility for criminal behavior, and the process of decision making in juries. These professionals include those with a medical degree, such as psychiatrists, neurologists, and neuropsychologists, as well as individuals without a medical degree, such as psychologists.Mental health professionals are frequently consulted in civil and criminal cases to help determine an individual's state of mind with regard to a crime, the validity of testimony before a court, or an individual's competence to stand trial or make a legal decision. Their input may also be vital to legal procedures for deciding whether to commit a person to an institution because of mental illness, or to allow a person to leave an institution for those who are mentally ill.
Forensic neuropsychology is a specialized area of forensic medicine that applies the functioning of the nervous system and brain to legal issues involving mind and behavior. Equipped with an improved understanding of how the brain works and influences behavior, neuropsychologists have increasingly been asked to provide testimony to courts attempting to determine whether a criminal act is a result of a nervous system dysfunction. They also testify as to the reliability of witness testimony given by Victims of Crime, the competency of individuals to stand trial, the likelihood that a condition of mental retardation or brain injury predisposed an individual to commit a crime, the possibility that an individual has verifiable memory loss, and various aspects of dementias and other brain disorders caused by AIDS, head injuries, and drugs, alcohol, and other chemicals.
In civil cases, the work of neuropsychologists has been used to determine whether a defendant's wrongdoing caused a plaintiff's injury. In family courts, neuropsychologists assess brain damage in children who have been physically abused.
Forensic psychologists provide expert testimony that touches on many of the same areas as that given by forensic psychiatrists and neuropsychologists. In addition, psychologists consult with the legal system on issues such as correctional procedures and crime prevention. In 1962, a U.S. court of appeals issued an influential decision that established the ability of a psychologist to testify as an expert witness in a federal court of law (Jenkins v. United States, 113 U.S. App. D.C. 300, 307 F.2d 637 [D.C. Cir. 1962]). Before that time, expert testimony on mental health was largely restricted to physicians.
Other Areas of Forensic Science
Forensic engineers provide courts with expertise in areas such as the design and construction of buildings, vehicles, electronics, and other items. Forensic linguists determine the authorship of written documents through analyses of handwriting, syntax, word usage, and grammar. Forensic anthropologists identify and date human remains such as bones. Forensic geneticists analyze human genetic material, or DNA, to provide evidence that is often used by juries to determine the guilt or innocence of criminal suspects. Forensic phoneticians deal with issues such as the validity of tape-recorded messages, the identification of speakers on recorded messages, the enhancement of recorded messages, the use of voiceprints, and other aspects of Electronic Surveillance.
Federal Bureau of Investigation. 1994. Handbook of Forensic Science. Washington, D.C.: U.S. Government Printing Office.
Genge, N.E. 2002. The Forensic Casebook: The Science of Crime Scene Investigation. New York: Ballantine Books.
Hollien, Harry. 1990. The Acoustics of Crime: The New Science of Forensic Phonetics. Plenum.
Marriner, Brian. 1991. On Death's Bloody Trail: Murder and the Art of Forensic Science. New York: St. Martin's Press.
Vacca, John. 2002. Computer Forensics: Computer Crime Scene Investigation. Hingham, Mass.: Charles River Media.
Valciukas, José A. 1995. Forensic Neuropsychology: Conceptual Foundations and Clinical Practice. Binghamton, N.Y.: Haworth.
Weiner, Irving B., and Allen K. Hess. 1987. Handbook of Forensic Psychology. New York: Wiley.