In Paris, French Army captain Alfred Dreyfus was wrongly convicted of treason in 1894 based on fabricated and misread handwriting evidence, and sentenced to life imprisonment on Devil's Island in French Guiana. The eventual exposure of evidence tampering, forgery, and institutional anti-Semitism led to Dreyfus's exoneration in 1906 after a decade-long campaign. The Dreyfus Affair became the defining nineteenth-century case on the corruption of evidence gathering and the misuse of forensic expertise to support predetermined verdicts.

The Dreyfus Affair was a seismic event in French and European literary culture. Émile Zola's open letter J'Accuse (1898) is among the most famous works of literary political intervention ever written. Proust, who attended the trial, wove the Affair into À la Recherche du temps perdu as a defining social trauma. The case radicalised a generation of French writers and poets, including those in the Symbolist movement, on questions of justice, evidence, and the state.