The judgement of the machines: disputing a vision test in a 1926 Shanghai courtroom

This essay examines how the interplay between diagnostic machines and patient experience reshaped the meaning of testing validity, through a 1926 malpractice lawsuit in colonial Shanghai. It traces how complaints of dizziness, a seemingly mundane side effect of new glasses, escalated into a legal and epistemic dispute over the validity of a vision test. Weaving together competing perspectives presented in court, the essay uncovers discrepancies between the examiner’s observations, the machine’s readings and the patient’s embodied experience. These clashes expose the fragility of the new regime of ‘scientific testing’ in the global city of Shanghai, which claimed authority from the emerging profession of optometry and a diagnostic machine known as the retinoscope. The case, I argue, marks an inflection point in the history of testing, as patient experience was recalibrated through new machines, re-legitimized in novel ways, and transformed into a generative feature of diagnostic practice itself.