The CSI effect describes the various ways in which the exaggerated portrayal of forensic science on crime television shows such as CSI: Crime Scene Investigation influences public perception. The term was first reported in a 2004 USA Today article describing the effect being made on trial jurors by television programs featuring forensic science.

It most often refers to the belief that jurors have come to demand more forensic evidence in criminal trials, thereby raising the effective standard of proof for prosecutors. While this belief is widely held among American legal professionals, some studies have suggested that crime shows are unlikely to cause such an effect, although frequent CSI viewers may place a lower value on circumstantial evidence. As technology improves and becomes more prevalent throughout society, people may also develop higher expectations for the capabilities of forensic technology. The CSI Effect has also re-popularized the forensic sector of the criminal justice system in the media and academia.