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The question of why people choose to commit crimes—often in the face of severe consequences—is at the root of criminal psychology, a branch of study that focuses on the intentions and behaviors of those who plan and carry out criminal acts. On the other hand, psychology itself has, over the years, engendered significant changes in how legal experts think about the crime and the law, as well as changes in how the mentally ill are treated by the criminal justice system.

Understanding Criminal Psychology

Criminal psychology does more than provide a glimpse into a criminal's psyche. It also plays a role in how the law is applied. In the courtroom, legal practitioners require a grasp of defendants' motivations and actions in order to render fair judgment. Forensic psychologists, as well as other mental health professionals, are often called upon to help clinically evaluate the mental states of people who break the law.

Psychology plays a role in police work as well. Criminal profilers—who aim to determine likely suspects through a mix of crime-scene analysis, investigative psychology, and other behavioral sciences—are often forensic psychologists or criminal anthropologists. Law enforcement agencies often rely on these experts to get inside the head of a potential culprit by identifying the perpetrator's likely personality type, lifestyle habits, and quirks.

What does a criminal psychologist do?

Criminal psychologists study the behaviors and motivations of criminals. As such, they may conduct research to determine why crimes occur, consult with police departments to identify suspects, or provide expert testimony in court cases. Criminal psychologists may also engage in criminal profiling.

Why is criminal psychology important?

Criminal psychology findings may help identify suspects, potentially allowing authorities to prevent future crime or catch a serial criminal. On a larger scale, understanding what motivates criminals to break the law—whether poverty, personality, or otherwise—is necessary for creating the societal conditions that may allow them to stop. 

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The Psychology of Crime

Exactly why people commit crimes, and what could deter them from doing so in the future, is of great interest to psychologists and law enforcement officers alike. So far, extensive research points to a complex mix of genetics, personality, life circumstances, and environmental factors.

Psychologists also undertake research—often working with individuals who have committed crimes or are the victims of crimes—to understand how criminals choose victims, whether it’s possible to protect oneself from certain types of crime, and what legal professionals and policymakers can do to stop crimes before they occur. But though great progress has been made in understanding the criminal psyche, there’s much that remains unknown about certain criminals’ motivations, as well as an element of randomness in who is victimized and who isn’t.

What causes a person to commit crimes?

Some individuals commit crimes out of necessity; others are driven by anger, rejection of authority, a manipulative personality, or psychopathic tendencies. While stereotypes that all mentally ill people are prone to crime is not accurate, there are instances where mental illness—such as psychosis, substance abuse, or severe bipolar disorder—could influence someone to break the law. 

How do criminals choose victims?

There is some evidence suggesting that criminals choose victims, at least in part, based on how they look or move. One study, for instance, found that criminals were more likely to label someone a potential victim if they appeared noticeably different from those around them or was moving in distracted, unusual ways.


How Psychology Influences the Law

Psychological and psychiatric findings have had a significant influence on the legal system, particularly since the beginning of the 20th century. Among significant changes include the push towards deinstitutionalization of the mentally ill, which coincided with the development of more advanced psychiatric medications and a greater understanding of the causes and potential treatments for mental disorders. In addition, the decriminalization of homosexuality in the U.S. was likely significantly influenced by the growing psychological acceptance that homosexuality—and more recently, being transgender—are not mental disorders.

In addition, legal professionals—including lawyers, police officers, and judges—now regularly consult with psychologists to assess defendants’ state of mind and provide treatment if necessary. This branch of psychology, known as forensic psychology, has grown exponentially in recent years.

How are psychology and the law related?

Psychology and the law both examine human behavior—the first seeks to understand it, and the second seeks to regulate it where necessary. Psychologists study people’s needs and desires, why they follow laws, and how they understand fairness and justice—and these findings, in turn, can help policymakers write laws that are in the public interest.

Why do most people obey the law?

They may be deterred by possible consequences, see the law as a legitimate authority, obey the law so as to better coordinate with others around them and society at large, or they may do it to signal their beliefs or morality. For most law-abiding people, their reasoning is likely a combination of the above factors.

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