Legal Psychology: History, What It Studies, Branches, Case Examples

The  legal psychology  is a field of study that seeks to apply knowledge of traditional psychology in legal institutions, and in contexts that have to do with the law. Its objective is to help legal professionals to better carry out their work by providing them with tools derived from the study of human behavior.

Thus, for example, legal psychology seeks to meet objectives such as better understanding memory to determine how to act in front of eyewitnesses, so that more accurate decisions can be made in cases in which they offer the main evidence.

Along with forensic psychology, legal psychology is part of what is known as “psychology and law.” This field of knowledge began to gain importance in the 1960s, in an attempt by lawyers, judges, and mental health professionals to improve the justice system. Despite having its origin in the United States, it soon spread throughout Europe and throughout the Western world.

At present, legal psychology is one of the most important branches of this science, with more and more professionals in this area who collaborate closely with judges, lawyers and other workers in the justice sector. Although there are some critical voices towards this discipline, its relevance has not stopped growing in recent years.


First signs

Legal psychology is a discipline of fairly recent appearance, since it has been in existence officially only since the second half of the 20th century. However, the interest of mental health professionals in the field of justice appeared much earlier.

It is considered that the first publications that could be framed within this discipline occurred at the end of the 18th century, when several researchers began to write about different elements that differentiated criminals from normal people. This occurred during the height of the psychology of individual differences.

For example, Mckeen Cattell (one of the leading exponents of the psychology of individual differences) published a study in which he investigated different judicial interrogations to better understand the psychology of testimony.

In addition to this, the experts of this time began to recognize the need to use the discoveries made by psychology (which was a newborn science at that time) to better understand criminals and help in the exercise of judicial practice.

During the nineteenth and early twentieth centuries, legal psychology had not yet been established as a separate discipline, but more and more studies, research, and publications related to this topic were being conducted.

Birth of legal psychology

Already in the 1940s, psychologists began to intervene more actively in the development of different legal activities. However, it was not until the 1950s that they began to testify playing the role of experts in different trials, which definitely marked the birth of legal psychology as an independent discipline.

During this decade and the following, in addition, there was a great increase in studies related to the psychology of different legal aspects. For example, in the 1960s social psychology focused on investigating phenomena such as crime, violence, altruism or respect for the rules.

Finally, in the 1970s, legal psychology was divided into two different fields: forensic and legal. At present there are numerous specialized schools in each of these disciplines, as well as publications dedicated exclusively to one of them.

What does legal psychology study? Object of study

Judge.  Male judge in a courtroom striking the gavel

Like the rest of the specialties of this science, legal psychology focuses on the study of human behavior and the different aspects that derive from it. In practice, this is specified in three different fields: study of behavior related to crime, conflict resolution or mediation, and evaluation and improvement of laws.

– Study of behaviors related to crime

The first field of application of legal psychology is the study of different aspects of human behavior and mentality that have to do with legal activity.

Thus, in this area we can find research on the psychological characteristics of criminals, but also on those of witnesses or legal professionals themselves.

In this case, legal psychology is largely based on research from other related branches of the study of human behavior, such as basic or social psychology. For example, discoveries about memory or peer pressure can be used to better understand the role of witnesses in court.

The objective behind this field of application is to better understand all the pieces that make up a judicial process. In this way, specialist psychologists will be able to work with legal professionals to create more concrete and effective rules, as well as discover better ways to enforce them and punish those who break them.

– Conflict resolution or mediation

Another of the most important fields of application of legal psychology is mediation and the resolution of conflicts that may arise in this area. In some cases, legal psychologists and forensics have to go as expert witnesses to trials to determine the veracity of different evidence, or to conduct studies on those involved in a case.

For example, a legal psychologist might determine that a witness is not telling the truth because of a memory distortion, so the judge might decide to ignore their testimony as evidence.

– Evaluation and improvement of laws

The last field of application of legal psychology is also the most recent one. Professionals in this field can study existing laws and their relationship to the human mind, in such a way that they are able to offer suggestions for improvement to increase their effectiveness and reduce their unwanted effects.

For example, within social psychology, different mechanisms have been studied through which to generate greater collaboration with authority and fewer crimes.

By applying this data, a legal psychologist can help law professionals avoid crimes or create more effective punishments for those who break the rules.

Branches of legal psychology


– Expert witnesses

One of the most common functions of legal psychologists is to act as expert witnesses in different legal processes. Thus, these professionals have to give their opinion on different psychological aspects such as the memory of the witnesses, identity confusion, or the existence of cognitive biases within the jury.

– Counseling

Legal psychologists can also fulfill an advisory role within legal systems. In this sense, they often help judges, lawyers and other professionals make decisions within a case based on what they know about the behavior of the human mind.

In addition to this, legal psychologists can also educate members of the legal system on different aspects of human psychology relevant to a specific case, such as the existence of certain mental pathologies.

– Development of laws

Legal psychologists can also participate in law making through empirical research on a particular phenomenon. These experts would be in charge of evaluating current laws and suggesting changes or improvements based on the functioning of human nature.

– Consulting

Legal psychology can also be used to assist in the training process for legal professionals. Thus, an expert psychologist in this area can participate in the training of judges or lawyers using techniques such as  role playing , group dynamics or their psychological preparation.

– Investigation

Most legal psychologists work for research centers, such as universities, conducting empirical studies and teaching.

Their work in this sense is twofold: on the one hand they try to better understand certain aspects of the human mind related to law, and on the other they have to be able to disseminate their discoveries.

Examples of legal psychology cases

– Ted Bundy

One of the most famous cases in recent history was that of Ted Bundy, a serial killer who murdered crowds of people in the United States before being finally arrested.

His case could not have been solved without the help of a team of forensic and legal psychologists, who recreated his profile based on the evidence they found and the nature of his crimes.

Finally, thanks to the information they collected and the help of different witnesses, especially one of Bundy’s ex-partners, the legal psychologists in the case were able to give the police a series of crucial clues and link this murderer to various crimes. without resolving.

– John Wayne Gacy

The “killer clown” John Wayne Gacy was arrested mainly because of the suspicions and complaints of his neighbors, but without the help of the legal psychologists involved in his case he would not have been convicted of all the crimes he committed.

The team of experts dedicated to his case discovered the motives behind his murderous behavior, and managed to unravel his plans regarding and discover where he hid the bodies of his victims.


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  3. “What are the Differences Between Legal Psychology and Forensic Psychology?” in: Psychology School Guide. Retrieved on: April 27, 2020 from Psychology School Guide:
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