In studying the multifaceted and ambiguous operation of the insanity defence in the past, is it best to conduct a long-term quantitative analysis or to examine a selection of trials in depth? Through the study of one criminal trial held in a Victorian Supreme Court in 1914, the subtle interactions between legal, medical and cultural systems of knowledge can be identified and unpacked. In this period, defendants submitted the insanity defence in increasing numbers. However, tension often existed between medical and lay judgements of criminal insanity. Jurors, witnesses, Judges, police and the wider public often imputed insanity where no insanity defence had been submitted and no medical experts had identified illness. Using trial documents and press coverage, this paper will investigate how conflicting discourses of insanity affected one trial in 1914. In doing so, the study will shed light on a broader trend of ambiguity and conflict concerning criminal insanity across the period. Ultimately, the paper will address how post-trial public activists used the language of insanity to save offenders from the death penalty, and how cultural assumptions regarding class, race, gender and crime often played a large role in where insanity was advocated and where it was disbelieved.