Revisiting 'Dreyfus': A More Complete Account of a Trial by Mathematics

Abstract:     
Legal literature and case law depicts the infamous conviction of Alfred Dreyfus for treason and espionage in 1899 as a prime example of the irresistible power of even grossly fallacious mathematical demonstrations to overwhelm a legal tribunal. This essay shows that Dreyfus is not a case of mathematics run amok, unchecked and uncomprehended. To the contrary, the defects in the mathematical proof were dramatically exposed, and this evidence did not lead Dreyfus's judges to condemn him. This history undercuts the reliance of modern courts and commentators on Dreyfus as an indication or illustration of the alleged dangers of probability evidence in criminal cases.

Keywords: Legal history, Dreyfus, probability, statistics, handwriting, scientific evidence

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