After his exclusion from the literary review Tel Quel, which he co-founded with Philippe Sollers, Hallier went on to publish novels and satirical pamphlets, and created the controversial newspaper L'Idiot International.

While the Hallier family has ancient Breton roots on his father's side, he later claimed in his novel L'évangile du fou (1986) that his mother had Alsatian and Jewish heritage.

Deeply stirred by the 1968 student riots in Paris, Hallier disclosed left-wing political views in the partly autobiographical La Cause des peuples (1972).

He engaged into politics full-time and started the first, leftist version of his paper, L'Idiot international, partly funded at first by Jean-Paul Sartre and Simone de Beauvoir.

Politically, Hallier was successively a Maoist, an admirer of Fidel Castro, while at the same time getting close to Jacques Chirac, and supported Pinochet after his return from his expedition to Chile.

[2] For a time, he was close to François Mitterrand, who successfully ran for President in 1981 for the Socialist Party (PS), but later opposed him, threatening to reveal the existence of his illegitimate daughter Mazarine Pingeot.