An expert witness, particularly in common law countries such as the United Kingdom, Australia, and the United States, is a person whose opinion by virtue of education, training, certification, skills or experience, is accepted by the judge as an expert. The judge may consider the witness's specialized opinion about evidence or about facts before the court within the expert's area of expertise, to be referred to as an "expert opinion". Expert witnesses may also deliver "expert evidence" within the area of their expertise. Their testimony may be rebutted by testimony from other experts or by other evidence or facts.
In law, a witness is someone who, either voluntarily or under compulsion, provides testimonial evidence, either oral or written, of what they know or claim to know.
Forensic psychology is the practice of psychology applied to the law. Forensic psychology is the application of scientific knowledge and methods to help answer legal questions arising in criminal, civil, contractual, or other judicial proceedings. Forensic psychology includes research on various psychology-law topics, such as jury selection, reducing systemic racism in criminal law, eyewitness testimony, evaluating competency to stand trial, or assessing military veterans for service-connected disability compensation. The American Psychological Association's Specialty Guidelines for Forensic Psychologists reference several psychology subdisciplines, such as social, clinical, experimental, counseling, and neuropsychology.
Criminal psychology, also referred to as criminological psychology, is the study of the views, thoughts, intentions, actions and reactions of criminals and suspects. It is a subfield of criminology and applied psychology.
Weapon focus is the concentration on a weapon by a witness of a crime and the subsequent inability to accurately remember other details of the crime. Weapon focus is a factor that heavily affects the reliability of eyewitness testimony. This effect involves a witness to a crime diverting his or her attention to the weapon the perpetrator is holding, thus causing memory impairments and leaving less attention for other details in the scene, such as the attacker’s face, clothing or vehicle.
Forensic psychiatry is a subspeciality of psychiatry and is related to criminology. It encompasses the interface between law and psychiatry. According to the American Academy of Psychiatry and the Law, it is defined as "a subspecialty of psychiatry in which scientific and clinical expertise is applied in legal contexts involving civil, criminal, correctional, regulatory, or legislative matters, and in specialized clinical consultations in areas such as risk assessment or employment." A forensic psychiatrist provides services – such as determination of competency to stand trial – to a court of law to facilitate the adjudicative process and provide treatment, such as medications and psychotherapy, to criminals.
A miscarriage of justice occurs when an unfair outcome occurs in a criminal or civil proceeding, such as the conviction and punishment of a person for a crime they did not commit. Miscarriages are also known as wrongful convictions. Innocent people have sometimes ended up in prison for years before their conviction has eventually been overturned. They may be exonerated if new evidence comes to light or it is determined that the police or prosecutor committed some kind of misconduct at the original trial. In some jurisdictions this leads to the payment of compensation.
In United States federal law, the Daubert standard is a rule of evidence regarding the admissibility of expert witness testimony. A party may raise a Daubert motion, a special motion in limine raised before or during trial, to exclude the presentation of unqualified evidence to the jury. The Daubert trilogy are the three United States Supreme Court cases that articulated the Daubert standard:
In United States and Canadian law, competence concerns the mental capacity of an individual to participate in legal proceedings or transactions, and the mental condition a person must have to be responsible for his or her decisions or acts. Competence is an attribute that is decision-specific. Depending on various factors which typically revolve around mental function integrity, an individual may or may not be competent to make a particular medical decision, a particular contractual agreement, to execute an effective deed to real property, or to execute a will having certain terms.
Forensic hypnosis is the use of hypnosis in the investigative process and as evidence in court which became increasingly popular from the 1950s to the early 1980s with its use being debated into the 1990s when its popular use mostly diminished. Forensic hypnosis's uses are hindered by concerns with its reliability and accuracy. The United States Department of Justice states that hypnosis may be occasionally used in investigation, but that the method faces "serious objections" and that information from hypnosis may be considered inadmissible. Forensic hypnosis has been considered for several uses including: hypnotic memory enhancement, evaluating a defendant's mental state, determining if a subject is telling the truth, preparing a witness for trial, determining if one is feigning trauma or a mental injury, and supporting the defense in a criminal case. Some of these uses have found more support than others as academic psychologists have reviewed these. While psychologists may find it appropriate to use memory enhancement to help in finding leads in the investigation process which should lead to uncovering more concrete evidence, its use in determining if a subject is telling the truth has been widely criticized.
Forensic psychotherapy is the application of psychological knowledge to the treatment of offender-patients who commit violent acts against themselves or others. This form of treatment allows for a therapist to potentially understand the offender and their mental state. It gives the individual providing treatment the opportunity to examine further whether the offender’s criminal behavior was a conscious act or not, what exactly their association with violent behavior is, and what possible motives could have driven them. The discipline of forensic psychotherapy is one that requires the involvement of individuals other than simply the therapist and patient. A therapist may collaborate with other professionals, such as physicians, social workers, and other psychologists in order to best serve the offenders’ needs. Whether the treatment is successful or not relies on a multitude of things, but typically ensuring that a systemic approach is taken and that all involved in the treatment process are well informed and supportive has proven to be the most effective. In addition to group work, forensic psychotherapy may also involve therapeutic communities, individual interaction with victims as well as offenders, and family work. In order for this specialized therapy to be as effective as possible, it demands the compliance of not only the patient and therapist, but of the rest of society as well. The main focus of forensic psychotherapy is to obtain a psychodynamic understanding of the offender in order to attempt to provide them with an effective form of treatment. Guidelines have been set to ensure proficiency in the field of Forensic Psychology.
In eyewitness identification, in criminal law, evidence is received from a witness "who has actually seen an event and can so testify in court".
An ultimate issue in criminal law is a legal issue at stake in the prosecution of a crime for which an expert witness is providing testimony.
Richard C. Waites, J.D., Ph.D.,, a noted board certified trial attorney and social psychologist, is an internationally recognized expert in jury and courtroom decision maker research, a field he helped to develop and that he continues to advance.
Barefoot v. Estelle, 463 U.S. 880 (1983), is a United States Supreme Court case. The Court ruled on the admissibility of clinical opinions given by two psychiatrists hired by the prosecution in answer to hypothetical questions regarding the defendant's future dangerousness and the likelihood that he would present a continuing threat to society in this Texas death penalty case. The American Psychiatric Association submitted an amicus curiae brief in support of the defendant's position that such testimony should be inadmissible and urging curtailment of psychiatric testimony regarding future dangerousness and a prohibition of such testimony based on hypothetical data.
Saul Kassin is a distinguished professor of psychology at John Jay College of Criminal Justice - City University of New York and Massachusetts Professor Emeritus of Psychology at Williams College in Williamstown, Massachusetts.
Eyewitness testimony is the account a bystander or victim gives in the courtroom, describing what that person observed that occurred during the specific incident under investigation. Ideally this recollection of events is detailed; however, this is not always the case. This recollection is used as evidence to show what happened from a witness' point of view. Memory recall has been considered a credible source in the past, but has recently come under attack as forensics can now support psychologists in their claim that memories and individual perceptions can be unreliable, manipulated, and biased. As a result of this, many countries, and states within the United States, are now attempting to make changes in how eyewitness testimony is presented in court. Eyewitness testimony is a specialized focus within cognitive psychology.
Gail S. Goodman is an American psychologist, known as one of the first in her field to study children's roles in the legal system, specifically children's eyewitness testimony pertaining to the Sixth Amendment. Her awards for her contributions to research, writing, and teaching include the American Psychological Association Award for Distinguished Contributions to Psychology in the Public Interest in 2017. Her involvement includes being cited in United States Supreme Court cases, which is rare for psychologists.
John C. Yuille was a Canadian psychologist whose research interests include forensic psychology, victim and witness memory, suspect memory, trauma and memory, stress and memory, child sexual abuse, interview techniques, serial crimes, and credibility assessment.
Gary L. Wells is an American psychologist and an internationally recognized pioneer and scholar in eyewitness memory research. Wells is a professor at Iowa State University with a research interest in the integration of both cognitive psychology and social psychology and its interface with law. He has extensive research on lineup procedures and the reliability and accuracy of eyewitness identification, and has been widely acknowledged in both the field of psychology and the criminal justice system. Wells has received many awards and honorary degrees and been widely recognized for his work and contributions to psychology and the implications his research has made to the legal system.
