He held a series of ministerial portfolios after the Socialist victory in 1981, especially as minister of state for the interior and decentralization.

A lawyer and member of the French Section of the Workers' International (SFIO), Defferre was involved in the Brutus Network, a Resistance Socialist group, during World War II.

It corresponded with Defferre's profile (L'Express co-founder Jean-Jacques Servan-Schreiber being a well known advocate of a Third Force alliance of socialists, Christian democrats and Radicals).

But, failing to create an SFIO-MRP-Radical Party federation, Defferre had to give way to François Mitterrand, whose preferred strategy for the Socialists was the formation of a left-wing coalition including the PCF.

Defferre yelled ‘Taisez-vous, abruti!‘ (‘Shut up, stupid!’) at Ribière following an argument in the French National Assembly.

The failure of Defferre prompted the birth of the new Socialist Party (PS) and buried the idea of an alliance with the centre-right.