Abstract: The insanity defense is a legal standard that deals with determining culpability for criminal acts. When met, it absolves the individual of a criminal act they committed, although they are typically mandated to a secure hospital for treatment. As defined in federal jurisdictions under 18 U.S.C. §17(a), insanity “is an affirmative defense under any Federal Statute that, at the time of the commission of the acts constituting the offense, the defendant as a result of severe mental disease or defect, was unable to appreciate the nature and quality or the wrongfulness of his acts.” The presence of a mental disease or defect is considered a threshold condition, meaning it first must be determined if a mental disease or defect exists, and then determined if that condition was severe enough to cause the individual to be unable to appreciate the wrongfulness of their acts. Some states have added a volitional component to their insanity defense. This prong deals with if an individual, as the result of a threshold condition, lacks the substantial capacity to conform their conduct to the law. However, it must be noted that the insanity defense is unpopular with many state legislatures. Four states (Idaho, Kansas, Montana, and Utah) have abolished the insanity defense. Forensic psychiatrists and psychologists are often tasked with conducting these retrospective evaluations. This is a difficult task, as it requires the forensic practitioner to reconstruct an individual’s mental state as it relates to the alleged criminal act days, months, or even years after the event. To conduct these evaluations properly often requires a substantial amount of collateral information, including previous mental health records, academic records, employment records, and, most recently, information gleaned from social media, that can assist the evaluator in the reconstruction of an individual’s mental state. This bibliography emphasizes the complexity of the insanity defense and its complicated and lengthy history. However, readers are encouraged to further explore articles and books to elucidate the lengthy legal history of the insanity defense and complexities in conducting insanity evaluations.