Forensic psychology: A field of psychology that deals with all aspects of human behaviour as it relates to the law or legal system

Forensic psychology has a relatively short history, dating back roughly to the late nineteenth century.


Some of the first experiments were those of James Cattell at Columbia University in New York. Cattell conducted experiments looking at what would later be called the psychology of eyewitness testimony. Also looked at memory accuracy and how well we can accurately report what we see.

Famous French psychologist Alfred Binet presented numerous studies in which he showed that the testimony provided by children was highly susceptible to suggestive questioning techniques. Also part of the stanford-binet IQ test.

German psychologist William Stern. The “reality experiment” that is now commonly used by eyewitness researchers to study eye witness recall and recognition can in fact be attributed to Stem. Using this research paradigm, participants are exposed to staged events and are then asked about the event. Stem found that the testimony of participants was often incorrect. In addition, he found that recall was the worst for portions of the event that were particularly exciting. This led him to conclude that emotional arousal can have a negative impact on the accuracy of a person's testimony.


The crimes attracted a great deal of attention from the press of the time, and Schrenck-Notzing testified that this extensive pretrial press coverage could influence the testimony of people by causing what he called retroactive memory falsification. This term was used to refer to a process whereby people confuse actual memories of events with the events described by the media.

Varendonck was able to demonstrate that many of the children were easily led by suggestive questioning. Varendonck's conclusion that was offered to the court was that the testimony provided by the children in this case was likely inaccurate and that children, as a group, were prone to suggestion.


Considered by many to be the father of forensic psychology, Hugo Munsterberg is best known for his controversial book On the Witness Stand, which helped push North American psychologists into the legal arena.


In the early to mid-1900s psychologists in the United States began to be more heavily involved in the judicial system as expert witnesses.

The first time this happened was in the case of State v. Driver in 1921. The West Virginia case involved the attempted rape of a young girl and the court accepted expert evidence from a psychologist in the area of juvenile delinquency. In its ruling the court stated, “It is yet to be determined that psychological and medical tests are practical, and will detect the lie on the witness stand”

More recent U.S. court cases were also enormously important in the history of forensic psychology. Brown v. Board of Education (1954) was one such case. This well-known case challenged the constitutionality of segregated public schools. There was a detremental effect on the black children and they felt psychologically inferior and thus an integrated school would be best for learning. This was the first time that psychological research had been cited in a U.S. Supreme Court decision, and while people have since debated how much weight the court really put on this research in reaching its decision, some have argued that this event helped validate psychology as a science.

Other important cases in the United States expanded the role of psychologists in court, with rulings that allowed psychologists to provide opinions on matters that were traditionally reserved for physicians. In People v. Hawthorne (1940), for example, a psychologist was permitted, on appeal, to provide an opinion about the mental state of the defendant at the time of his offence. . However, the trial judge instructed the jury to disregard the testimony from the psychologists because “psychologists were not qualified to give expert testimony on the issue of mental disease.” The case was appealed. As part of the appeal, the APA Provided a report to the court stating their view that psychologists are competent to provide opinions concerning the existence of mental illness.


The most significant contributions by psychologists in Canada have arguably been in the area of corrections. One person who has played a particularly important role in developing this area of research and practice is Dr. Paul Gendreau. Gendreau's research has influenced how offenders are dealt with in Canada and around the world. Gendreau has conducted numerous studies that have clearly shown that get-tough strategies commonly thought to be useful in deterring crime often have little deterrent effect and can even lead to higher rates of reoffending.

Compared to The United States, where psychologists have been permitted to conduct assessments of fitness to stand trial and criminal responsibility since the mid-1900s, Canadian courts have tended to rely upon physicians.


The APA formally recognized forensic psychology as a specialty discipline in 2001.


Experts in this area still don't agree on what the field should be called, let alone how it should “be defined.

One of the most commonly cited examples of a broad definition of forensic psychology is the one proposed by Bartol and Bartol (2006). They defined the discipline as “(a) the research endeavor that examines aspects of human behaviour directly related to the legal process... and (b) the professional practice of psychology within, or in consultation with, a legal system that embraces both civil and criminal law”


Three roles in particular are important to discuss: the forensic psychologist as clinician, the forensic psychologist as researcher, and the forensic psychologist as legal scholar.

Clinical forensic psychologists: psychologists who are broadly concerned with the assessment and treatment of mental health issues as they pertain to the law or legal system.

  • A frequent task for this type of forensic psychologist might involve the assessment of an offender to determine if he or she is likely to pose a risk to the community if released from prison.
  • Conducting divorce and child custody mediation
  • Providing expert testimony on questions of a psychological nature
  • Conducting critical incident stress debriefings with police officers
  • Facilitating treatment programs for offenders

Forensic psychiatry: A field ot medicine that deals with all aspects of human behaviour as it relates to the law or legal system

Experimental forensic psychologists: psychologists who are broadly concerned with the study of human behaviour as it relates to the law or legal system

  • Examining the effectiveness of risk-assessment strategies
  • Determining what factors influence jury decision making
  • Developing and testing better ways to conduct eyewitness lineups
  • Evaluating offender and victim treatment programs
  • Examining the effect of stress management interventions on police officers


Psychology and the law: The use of psychology to examine the operation of the legal system

Psychology in the law: The use of psychology in the legal system as that system operates

Psychology of the law: The use of psychology to examine the law itself


In this relationship, “psychology is viewed as a separate discipline [to the law], examining and analysing various components of the law [and the legal system] from a psychological perspective

Frequently asked questions

  • “Are eyewitnesses accurate?”
  • “Do certain interrogation techniques cause people to falsely confess?”
  • “Are judges fair in the way they hand down sentences?”
  • “Is it possible to accurately predict if an offender will be violent when released from prison?”


Once a body of psychological knowledge exists in any of the aforementioned areas of study, that knowledge can be used in the legal system by psychologists, lawyers, judges, and others.

  • It might consist of a psychologist in court providing expert testimony concerning some issue of relevance to a particular case
  • Psychology in the law might consist of a police officer using his or her knowledge of psychology in an investigation.


Addresses questions such as:

  • “Does the law reduce the amount of crime in our society?”
  • “Why is it important to allow for discretionary decision making in the Canadian criminal justice system?”
  • “What impact should court rulings have on the field of forensic psychology?”


Since the field of forensic psychology has become more widely accepted, forensic psychologists have increasingly been asked to provide expert testimony in court.

The variety of topics that forensic psychologists can now testify about in many countries is very broad indeed, including custody issues, malingering and deception, accuracy of eyewitness identification, the effects of crime on victims, and the assessment of dangerousness (to name a few).


Expert witness: A witness who provides the court with information (often an opinion on a particular matter) that assists the court in understanding an issue of relevance to a case.

These opinions and inferences must always fall within limits of expert witnesses' areas of expertise, which they typically get through specialized training and experience, and the testimony must be deemed reliable and helpful to the court.

The expert witness is supposed to be there as an educator to the judge and jury, not as an advocate for the defence or the prosecution


According to Hess (1999), psychology and law differ along at least 7 different dimensions:

  1. Knowledge
  2. Methodology
  3. Epistemology
  4. Criteria
  5. Nature of law.
  6. Principles
  7. Latitude

Currently, little attempt has been made to understand these differences between psychology and law, or their implications for the field of forensic psychology. Once we gain such an understanding, perhaps forensic psychologists will be in a better position to assist courts with the decisions they are required to make


In order for forensic psychologists to provide expert testimony in court, they must meet certain criteria.

In fact, until quite recently, the admissibility of expert testimony in the United States was based on a decision handed down by the courts in Frye v. United States (1923). Frye was being tried for murder and the court rejected his request to admit the results from a polygraph exam he had passed. On appeal, the court also rejected requests to allow the polygraph expert, William Marston, to present evidence on Frye's behalf. The polygraph wasn't yet established in its particular field.

General acceptance test: A standard for accepting expert testimony, which states that expert testimony will be admissible in court if the basis of the testimony is generally accepted within the relevant scientific community

Daubert v. Merrell Dow pharmaceuticals, Inc. (1993). Daubert sued Merrell Dow because he believed a morning sickness drug his mother ingested while pregnant, which was produced by the company, led to His birth defects. , At trial, MerrelJ Dow presented experts who provided evidence that the use of the drug Bendectin does not result in birth defects. In turn, Daubert provided evidence from experts who claimed that Bendectin could lead to birth defects. The state court and the appeal court both rejected the testimony provided by Dauberts experts on the basis that the methods they used to arrive at their results were not generally accepted by the scientific community. On appeal before the U.S. Supreme court, Daubert's lawyers challenged the state and appeal courts' interpretation of “general acceptance.”

Daubert criteria: A standard for accepting expert testimony, which states that scientific evidence, is valid if the research on which it is based has been peer reviewed, is testable, has a recognized rate of error, and adheres to professional standards

Mohan criteria: A standard for accepting expert testimony, which states that expert testimony will be admissible in court if the testimony is relevant, is necessary for assisting the trier of fact, does not violate any exclusionary rules, and is provided by a qualified expert


  1. The history of forensic psychology is marked by many important milestones, in both the research laboratory and the courtroom. Early research included studies of testimony and suggestibility, and some of the early court cases in Europe where psychologists appeared as experts dealt with similar issues. Hugo Munsterberg played a significant role in establishing the field of forensic psychology in North America, and by the early 1900s, forensic psychologists were active in many different parts of North American criminal justice system, including in Canada. Currently, forensic psychology is viewed as a distinct and specialized discipline, with its own textbooks, journals, and professional associations.
  2. Forensic psychology can be defined in a narrow or broad fashion. Narrow definitions usually focus only on the clinical or experimental aspects of the field, whereas broad definitions are less restrictive and encompass both aspects.
  3. Forensic psychologists can play different roles. Clinical forensic psychologists are primarily interested in mental health issues as they pertain to law. Experimental forensic psychologists are interested in studying any aspect of human behaviour that relates to the law (e.g., eyewitness memory, jury decision making, and risk assessment).
  4. Psychology can relate to the field of law in. three ways, psychology and the law refers to the use of psychology to study the operation of the legal system. Psychology in the law refers to the use of psychology within the legal system as it operates. Psychology of the law refers to the use of psychology to study the legal system itself.
Expert witnesses differ from regular witnesses in that expert witnesses can testify about their opinions, whereas other witnesses can testify only as to what they know to be fact. In Canada, the criteria for determining whether an expert's testimony will be admitted into court relate to whether the testimony (1) is relevant, (2 ) goes beyond the common understanding of the court, (3) does not violate any exclusionary rules, and (4) comes from a qualified expert.