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How Forensic Psychology is Framing Our Legal System

The field of forensics is often associated with objective truths: fingerprints left on a murder weapon, DNA evidence taken from a toothbrush, crime scene investigators in lab coats collecting hairs and clothing fibers for further investigation. Another equally important component of forensics, however, lies in deciphering the motives of the accused. After all, the legal system—the police, lawyers, and judges that prosecute and defend people charged with crimes—know that DNA and fingerprints are not the only things that define us as unique individuals. Increasingly, forensic psychologists have been called upon to bridge the gap between psychology, defined as the study of human behavior and the law.

There are many points at which the field of psychology and the legal system intersect. A person convicted of a crime and found to be mentally ill, for example, will inevitably cross paths with several members of the psychological profession during the legislative process. The generally accepted definition of forensic psychology, though, limits the definition exclusively branch of psychology directly associated with legal decisions. Today, forensic psychology plays a critical role in our judicial system, from the initial apprehension of criminals to the appeals process that might eventually set them free.

Forensic psychology aims to help law professionals remove human error when handling trials. Lawyers, judges, jurors, and witnesses that populate the judicial system are often subject to personal biases. The dangers behind such biases stem from the fact that they are often subconscious manifestations of historical experiences. The role of forensic psychology, of course, is to gain insight into the human mind and utilize the insight to shape legal proceedings in an objective manner.

Forensic Psychology and Jury Selection

In the United States, both the prosecution and defense help select trial juries, and both sides often employ the use of jury consultants to aid in the selection process. Many of these consultants are from the field of psychology. These experts guide the law teams to ask potential jurors specific questions to determine the likelihood that they will favor one side or the other, a process known by the Latin phrase “voir dire.” Jury questionnaires ask questions about the jurors’ personalities, personal experiences, attitudes, education, and, perhaps most importantly in high-profile cases, prior knowledge of the case. Meanwhile, consultants pay close attention to nonverbal cues during the questioning, watching for facial expressions, head nods, and other signs that a juror has a bias toward one particular side. For example, a forensic psychologist could ask the jury questions probing at past experiences with confidentiality of trade agreements during a voir dire examination for a patent-infringement case.

Typically, defense teams are more likely than their opponents to hire jury consultants, but prosecution teams are increasingly using professionals to help them win cases. During the Scott Peterson murder trial, the prosecution hired jury consultant Howard Varinsky, who also worked with the prosecution on the Martha Stewart case. His work may have helped level the playing field against the defense’s expert Jo-Ellan Dimitrius, who some say had an instrumental role in the outcome of the O.J. Simpson trial. Scott Peterson was eventually convicted of murder.

The voir dire process remains as much of an art as a science; there is no guarantee that such indicators are reliable, but legal teams continue to rely on forensic psychologists and other experts in human behavior to help “stack the jury” in favor of their side.

Forensic Psychologists as Expert Witnesses

Forensic psychologists are often called to testify about the mental capacity of a defendant. Some high-profile trials involve the defense team seeking a verdict of “not guilty by reason of insanity.” While these cases are actually very rare, they tend to garner a lot of attention in the media. More commonly, psychologists are called upon to prove “diminished capacity,” which doesn’t necessarily change the verdict, but might result in a lesser sentence.

One of the most notable cases of the insanity defense was the 1982 trial of John Hinckley Jr., whose defense team successfully convinced a jury that he was insane when he attempted to assassinate President Ronald Reagan. Public outcry in the years following the trial led many states to restrict the use of the insanity defense or, in some cases, allow juries to find a defendant mentally ill but still guilty of committing a crime.[i] In all cases involving an insanity or diminished mental capacity defense, testimony of forensic mental health professionals is key to the outcome of the trial.

Forensic Psychologist as Reformer

An increasingly important role in forensic psychology in the courts is to question the veracity of traditional testimony, from confessions to eyewitness accounts to suspect identification. It has been known for decades that eyewitness testimony, despite the important role it plays in convincing members of the jury of a suspect’s guilt or innocence, is highly unreliable. Many psychologists, most notably Professor Gary Wells of the University of Iowa, have done exhaustive research in the field, proving that memory is not like a tape recorder, but is instead highly suggestible and prone to bias. Some of these findings have helped prompt reforms in evidence-gathering procedures such as police lineups, where reliability can be greatly improved with a few changes. Backed with mounds of evidence, the American Psychological Association (APA) has encouraged the courts to allow defendants to more easily challenge the reliability of witnesses. However, psychologists aren’t typically allowed to testify on the reliability of witnesses during trials, leaving such a judgment up to jury, and a recent Supreme Court decision upheld the fairness of this practice.

From the initial jury selection to the admittance of expert opinion, forensic psychologists hold prominent roles in virtually all steps of the legislative process. This trend has been driven by the increasingly scientific acumen that the field of psychology has adopted in recent years. In today’s high-stakes legal system, lawyers use every weapon in their arsenal to win their case. Forensic psychology has been a proven method at understanding the how the human brain affects criminal behavior. Below are two more contemporary cases that further exemplify how forensic psychology is shaping the field of law today.

  • Andrea Yates was accused in 2002 of drowning her five children in a bathtub. Initially found guilty, the Yates case was overturned as a result of psychiatrist Park Dietz’s materially false testimony during the trial. After the appeal, Yates was found not guilty by reason of insanity, allowing her to serve her sentence in a low-security mental health institution instead of prison.
  • Jared Loughner was accused of attempted assassination of Congresswoman Giffords of Arizona along with 49 other counts.  The latest ruling found Loughner unable to comprehend the proceedings against him, giving doctors four months to rehabilitate Loughner’s mental state. Christina Pietz, Loughner’s primary psychologist, recently reported that Loughner had gone through extensive changes since being accepted to the mental ward. Until he is found medically capable of understanding the charges against him, however, Loughner’s fate remains in the hands of expert psychologists such as Pietz.