Daniel Paul Schreber, a senior German Judge at the end of the 19th century, author of Memoirs of My Nervous Illness, wanted to become a woman. Diagnosed by Freud, without ever meeting this patient, as mad, the Judge was simultaneously made world famous and stigmatised as a lunatic. The diagnosis, taken up again by Lacan, excluded the Judge from any non-clinical reading. Schreber’s Law reverses this diagnosis and takes up the case of the Judge in the current climate of trans advocacy to argue that far from being mad, he was driven by transitional desire and his extra-judicial writings, the Memoirs, some poetry, an essay on legal doctrine should be taken seriously as a radical critique of morbus juridicus, the illness of law. The argument is that the Judge fell ill of law. He was sick of the iron cage of German jurisprudence and so broke out and inscribed a biting critique of the automatism of jurists, of the theology of legal positivism, and of affectless reason of law’s putative science.