Legal evaluation of criminal responsibility has a long and controversial history that has trended toward greater considerations of defendants' intelligence and other psychological factors. The authors examine a 1928 criminal case that illustrates legal intelligence assessments and expert psychological testimony related to the insanity defense in the United States at that time. James Deacons, a 15-year-old with a cognitive disability, provided multiple coerced and contaminated confessions to homicide and sexual assault. The judge then sought mental health and intelligence assessments of Deacons to evaluate the potential for an insanity defense or other consideration of Deacons' intelligence that could lead to treatment rather than prison. The authors review the biography of the experienced intelligence assessor, Eugene C. Rowe. The authors consider Rowe's preassessment biases, including eugenic biases and other proguilt biases, before examining Rowe's multiple violations of protocol. These violations inflated Deacons' intelligence test score and eliminated legal consideration of Deacons' intelligence
Deacons then pleaded guilty. The authors contrast the evaluation of Deacons with H. H. Goddard's (1914) evaluation of Jean Gianini, including distinct outcomes. The authors connect this case to the larger histories of the insanity defense, expert testimony by psychologists, and perceptions of people with low intelligence. (PsycInfo Database Record (c) 2025 APA, all rights reserved).