A comparison of insanity defense standards on juror decision making

Following the Hinckley acquittal, 17 states and the federal government made changes to the insanity defense, including revising the standard, reassigning the burden of proof, and altering the standard of proof. Two studies were conducted to determine whether the specific insanity standard (including the assignment of burden of proof and standard of proof) employed had a significant effect on mock jurors' verdicts. Participants' comprehension of insanity defense instructions was measured and the factors jurors used to decide whether to find the defendant not guilty by reason of insanity (NGRI) were also assessed. Participants' comprehension of insanity defense standards was very low. When asked to identify the factors they considered important in determining whether to find a defendant NGRI, only three elements of insanity defense standards were identified as significant. The results may have important implications for policy decisions regarding the insanity defense.