[2][3] Although his childhood was relatively poor, his brother Étienne Hubert de Cambacérès later became a cardinal, and his father later became mayor of Montpellier.

In 1774, Cambacérès graduated in law from the college d'Aix and succeeded his father as Councillor in the court of accounts and finances in Toulouse.

In 1792, he represented the department of Hérault at the National Convention which assembled and proclaimed the First French Republic in September 1792.

In revolutionary terms, Cambacérès was a moderate republican and sat left of center during the National Convention.

[6] During the trial of Louis XVI he protested that the Convention did not have the power to sit as a court and demanded that the king should have due facilities for his defence.

Nevertheless, when the trial proceeded, Cambacérès voted with the majority that declared Louis to be guilty, but recommended that the penalty should be postponed until it could be ratified by a legislative body.

[2] During 1795, he was employed as a diplomat and negotiated peace with Spain, the Grand Duchy of Tuscany, the Kingdom of Prussia and the Batavian Republic.

[5] Cambacérès was considered too conservative to be one of the five Directors who took power in the coup of 1795 and, finding himself in opposition to the Executive Directory, he retired from politics.

He supported the coup of 18 Brumaire (in November 1799) that brought Napoleon Bonaparte to power as First Consul, a new regime designed to establish a stable constitutional republic.

Nevertheless, he was given credit for the justice and moderation of the government, although the enforcement of conscription was increasingly resented towards the end of the Napoleonic Wars.

When the Empire fell in 1814, Cambacérès retired to private life but was later called upon during Napoléon's brief return to power in 1815.

During the Hundred Days, the short period of time when Napoleon returned from exile, Cambacérès served as the minister of justice.

The fact that he had opposed the execution of Louis XVI counted in his favor, and in May 1818 his civil rights as a citizen of France were restored.

The National Constituent Assembly revised French criminal law in 1791 and got rid of a variety of offenses inspired by religion, including blasphemy.

Since there was no public debate, its motives remain unknown (a similar state of affairs occurred during the early years of the Russian Revolution).

[13] Robert Badinter once mentioned in a speech to the French National Assembly, during debates on reforming the homosexual age of consent, that Cambacérès was known in the gardens of the Palais-Royal as "Tante Urlurette".