Define Forensic Science . . .
Although there are numerous ways by which to categorize the forensic science disciplines, the following is the categorization used by the National Institute of Justice:
1. general toxicology;
3. questioned documents;
4. trace evidence;
5. controlled substances;
6. biological/serology screening (including DNA analysis);
7. fire debris/arson analysis;
8. impression evidence;
9. blood pattern analysis;
10. crime scene investigation;
11. medicolegal death investigation; and
12. digital evidence.
Forensic pathology is considered a subspecialty of medicine.
The term “forensic science” encompasses a broad range of disciplines, each with its own distinct practices. The forensic science disciplines exhibit wide variability with regard to techniques, methodologies, reliability, level of error, research, general acceptability, and published material. Some of the disciplines are laboratory based (e.g., nuclear and mitochondrial DNA analysis, toxicology, and drug analysis); others are based on expert interpretation of observed patterns (e.g., fingerprints, writing
samples, toolmarks, bite marks). Some activities require the skills and analytical expertise of individuals trained as scientists (e.g., chemists or biologists); other activities are conducted by scientists as well as by individuals trained in law enforcement (e.g., crime scene investigators, blood spatter analysts, crime reconstruction specialists), medicine (e.g., forensic pathologists), or laboratory methods (e.g., technologists).
Errors and Fraud
In recent years, the integrity of crime laboratories increasingly has been called into question, with some highly publicized cases highlighting the sometimes lax standards of laboratories that have generated questionable or fraudulent evidence and that have lacked quality control measures that would have detected the questionable evidence. In one notorious case, a state-mandated review of analyses conducted by West Virginia State Police laboratory employee Fred Zain revealed that the convictions of more than 100 people were in doubt because Zain had repeatedly falsified evidence in criminal prosecutions. At least 10 men had their convictions overturned as a result.25 Subsequent reviews questioned whether Zain was ever qualified to perform scientific examinations.
Other scandals, such as one involving the Houston Crime Laboratoryin 2003, highlight the sometimes blatant lack of proper education and training of forensic examiners. In the Houston case, several DNA experts went public with accusations that the DNA/Serology Unit of the Houston Police Department Crime Laboratory was performing grossly incompetent work and was presenting findings in a misleading manner designed to unfairly help prosecutors obtain convictions. An audit by the Texas Department of Public Safety confirmed serious inadequacies in the laboratory’s procedures, including “routine failure to run essential scientific controls, failure to take adequate measures to prevent contamination of samples, failure to adequately document work performed and results obtained, and routine failure to follow correct procedures for computing statistical frequencies.”
The Innocence Project has documented instances of both intentional and unintentional laboratory errors that have lead to wrongful convictions, including:
• In the laboratory—contamination and mislabeling of evidence.
• In information provided in forensics reports—falsified results (including “drylabbing,” i.e., providing conclusions from tests that were never conducted), and misinterpretation of evidence.
• In the courtroom—suppression of exculpatory evidence; providing a statistical exaggeration of the results of a test conducted on evidence; and providing false testimony about test results.
Assertions of a “100 percent match” contradict the findings of proficiency tests that find substantial rates of erroneous results in some disciplines (i.e., voice identification, bite mark analysis).
In a FBI publication on the correlation of microscopic and mitochondrial DNA hair comparisons, the authors found that even competent hair examiners can make significant errors. In this study, the authors found that in 11 percent of the cases in which the hair examiners declared two hairs to be “similar,” subsequent DNA testing revealed that the hairs did not match, which refers either to the competency or the relative ability of the two divergent techniques to identify differences in hair samples, as well as to the probative value of each test.
The insistence by some forensic practitioners that their disciplines employ methodologies that have perfect accuracy and produce no errors has hampered efforts to evaluate the usefulness of the forensic science disciplines.
And, although DNA analysis is considered the most reliable forensic tool available today, laboratories nonetheless can make errors working with either nuclear DNA or mtDNA—errors such as mislabeling samples, losing samples, or misinterpreting the data.
No forensic method other than nuclear DNA analysis has been rigorously shown to have the capacity to consistently and with a high degree of certainty support conclusions about “individualization” (more commonly known as “matching” of an unknown item of evidence to a specific known source). In terms of scientific basis, the analytically based disciplines generally hold a notable edge over disciplines based on expert interpretation.
The “CSI Effect”
Media attention has focused recently on what is being called the “CSI Effect,” named for popular television shows (such as Crime Scene Investigation) that are focused on police forensic evidence investigation. The fictional characters in these dramas often present an unrealistic portrayal of the daily operations of crime scene investigators and crime laboratories (including their instrumentation, analytical technologies, and capabilities).
Cases are solved in an hour, highly technical analyses are accomplished in minutes, and laboratory and instrumental capabilities are often exaggerated, misrepresented, or entirely fabricated. In courtroom scenes, forensic examiners state their findings or a match (between evidence and suspect) with unfailing certainty, often demonstrating the technique used to make the determination. The dramas suggest that convictions are quick and no mistakes are made.
The CSI Effect specifically refers to the real-life consequences of exposure to Hollywood’s version of law and order. Jurists and crime laboratory directors anecdotally report that jurors have come to expect the presentation of forensic evidence in every case, and they expect it to be conclusive.
A recent study by Schweitzer and Saks found that compared to those who do not watch CSI, CSI viewers were “more critical of the forensic evidence presented at the trial, finding it less believable. Forensic science viewers expressed more confidence in their verdicts than did nonviewers.”
Prosecutors and defense attorneys have reported jurors second guessing them in the courtroom, citing “reasonable doubt” and refusing to convict because they believed that other evidence was available and not adequately examined.
Schweitzer and Saks found that the CSI Effect is changing the manner in which forensic evidence is presented in court, with some prosecutors believing they must make their presentation as visually interesting and appealing as such presentations appear to be on television. Some are concerned that the conclusiveness and finality of the manner in which forensic evidence is presented on television results in jurors giving more or less credence to the forensic experts and their testimony than they should, raising expectations, and possibly resulting in a miscarriage of justice. The true effects of the popularization of forensic science disciplines will not be fully understood for some time, but it is apparent that it has increased pressure and attention on the forensic science community in the use and interpretation of evidence in the courtroom.
8 Leading Causes of Wrongful Conviction:
- 1. Eyewitnes misidentification
- 2. Forensic blood analysis
- 3. Police misconduct
- 4. Defective/fraudulent science
- 5. False confessions
- 6. False witness testimony
- 7. Informants
- 8. DNA inconclusion
Forensic Associations and Societies:
American Academy of Forensic Sciences
American Board of Criminalistics
American Board of Forensic Anthropology
American Board of Forensic Odontology
American Board of Forensic Toxicology
American Society for Quality
American Society for Testing and Materials
American Society of Crime Laboratory Directors
American Society of Questioned Document Examiners
Association of Firearm & Tool Marks Examiners
Association of Forensic Quality Assurance Managers
California Association of Criminalistics
Canadian Society of Forensic Sciences
Council of Federal Forensic Crime Laboratory Directors
Forensic Science Society
International Association for Identification
International Association of Arson Investigators
International Association of Bloodstain Pattern Analysts
International Association of Coroners and Medical Examiners
International Association of Forensic Nurses
International Association of Forensic Toxicologists
Mid-Atlantic Association of Forensic Scientists
Midwestern Association of Forensic Scientists
National Association of Medical Examiners
National Center of Forensic Science
National Forensic Science Technology Center
New Jersey Association of Forensic Scientists
Northeastern Association of Forensic Scientists
Northwest Association of Forensic Scientists
Society of Forensic Toxicologists
Southern Association of Forensic Science
Southwestern Association of Forensic Scientists
Wisconsin Association for Identification
Above Highlights from:
- Strengthening Forensic Science in the United States: A Path Forward (pdf)
Other University Courses of Interest:
- Introduction to Forensic Science - University of Strathclyde
- Forensic Psychology - The Open University
- Forensic Science and Criminal Justice - University of Leicester
- Identifying the Dead - University of Dundee