Legal systems are necessary in any functioning society. Centuries ago, people realized that the only way to maintain a peaceful community was to develop a firm set of rules -- laws -- to punish transgressors. As laws have continued to evolve in societies around the world, psychological scientists have begun to investigate the psychological basis of many aspects of legal systems.
A new special issue of Current Directions in Psychological Science, a journal of the Association for Psychological Science, presents the current state of research on psychology and law.
Many lawyers rely on eyewitness identifications and expert testimony in the courtroom, but scientific research increasingly suggests that this evidence is often unreliable. Eyewitnesses may be influenced by a suspect's race and by feedback from law enforcement officers. Expert testimony may be similarly flawed. Studies have shown that experts are often biased to the side that requested their assistance and even when expert testimony is truly objective, the judge -- who is also susceptible to bias -- often has the final say in determining which testimony is admissible in a trial.
Successful interviews of witnesses and suspects are critical for an effective legal system. However, false confessions may result when police officers present fabricated evidence and lie to suspects -- a strategy known as the Reid technique. Psychological scientists have investigated alternative methods; for example, research suggests that false confessions may be reduced by the PEACE model, a method commonly used by officers in the United Kingdom which does not allow officers to misinform a suspect.
Aside from judges, juries play a key role in a number of legal systems around the world. Although all jurors enter the courtroom with some sort of implicit bias, research shows that juries are largely effective at considering evidence presented to them and applying the law.
While no legal system is perfect, scientific research may increase our understanding of the psychological underpinnings of suspect interviews, jury selection, and judges' decisions and thus help ensure that legal systems evolve in the most efficient direction.
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