He was a staunch democrat and Republican, and was opposed to the Bourbon Restoration and the monarchy of Louis Philippe I.

[1] He entered commerce at a young age, and headed a trading house in Marseille dealing in fabrics.

[1] In 1822 Ollivier was denounced for having taken part in a plot against the monarchy, was arrested and condemned to six months in prison and a fine.

[1] He left Marseille and moved to Paris, where he lived quietly and raised his large family.

[1] Ollivier was opposed to the lawsuits against Louis Blanc and Marc Caussidière after the June Days Uprising He was against restoration of civil imprisonment, and for abolition of the death penalty.

He was in favor of amnesty, against the ban on clubs, against appropriations for the expedition to Rome, and for abolition of the tax on drinks, He opposed the policy of Prince Louis Napoleon Bonaparte, and was one of the signatories of the motion for the impeachment of the president and his ministers due to the events in Rome.

Ollivier was not reelected to the Legislative Assembly, but continue to struggle for republican and radical ideas in his department.

[7] In 1859 Démosthène Ollivier was involved in a dispute over non-payment of a dowry that Marie d'Agoult had promised to pay the newly-wed couple.