Forensic psychologists perform a wide range of duties within the justice system. Their responsibilities include assessing a defendant's competency to stand trial and their state of mind, as well as providing psychological treatment to individuals in the criminal justice system. They also act as consultants in various legal matters, such as child custody cases, sentencing, and treatment recommendations. Furthermore, their expertise is utilized in advising on the validity of eyewitness and children's testimony, assisting with jury selection, and preparing witnesses for court.