The criminal justice process is unavoidably human. Police detectives, witnesses, suspects, and victims shape the course of investigations, while prosecutors, defense attorneys, jurors, and judges affect the outcome of adjudication. In this sweeping review of psychological research, Dan Simon shows how flawed investigations can produce erroneous evidence and why well-meaning juries send innocent people to prison and set the guilty free.

The investigator's task is genuinely difficult and prone to bias. This often leads investigators to draw faulty conclusions, assess suspects'...