Abstract
This article focuses on the cases of two British ex-servicemen who contracted malaria during or immediately after the First World War, were charged with murder in the 1920s, and pled insanity due to their malaria and long-term neuropsychiatric complications. One was found 'guilty but insane' and committed to Broadmoor Criminal Lunatic Asylum in June 1923, while the other was convicted and hanged in July 1927. It argues that, at a time when the medical community sought out the causes of mental disease in the physical body, medico-legal arguments about malaria and insanity were received inconsistently by inter-war British courts. Class, education, social status, institutional support and the nature of the crime all mattered, as they had in the diagnoses, treatment and trials of other ex-servicemen with psychiatric illnesses.