Forensic psychologists are often retained by attorneys to serve as the role of forensic expert witness. When working as an expert witnesses, forensic psychologists express opinions based on their specialized knowledge. As expert witnesses, forensic psychologists may base their testimony on information gathered solely for the purpose of testifying in the litigation, offer their opinion on the cause or consequences, interpret the action of other persons, draw conclusions of the basis of circumstances, comment on the likelihood of events, or state their beliefs regarding nonfactual issues.