Paul Léon Jourdain was born on 28 October 1878 in Altkirch, Alsace-Lorraine, then part of the German Empire.

He attended the Lycée Jansonde-Sailly for his secondary education, then joined the 119th infantry regiment in Le Havre for his military service.

[2] At the start of World War I (1914–18) Jourdain tried to reach France but was arrested by the German military authorities on 4 August 1914.

[2] Jourdain was the principal author of the first French social insurance bill, which was presented to the chamber by his successor as Minister of Labor, Charles Daniel-Vincent.

It included insurance for illness, maternity, death, disability and old age, and applied to all workers in commerce, industry and agriculture.

On 10 July 1940 he voted in favor of the constitutional law that gave full powers to Marshal Philippe Pétain.