De Ladebat represented a danger to individuals in compromising or corrupt positions of power in need of enormous financial support. His personal honesty, thoroughness, and devout Protestantism made him a serious challenge to the Directory. Along with Boissy d'Anglais, he unceasingly denounced licentiousness and bureaucratic waste. De Ladebat was President of the Council of Ancients at the time of the 18 Fructidor coup against the new moderate majority on the Councils. He was later deported to French Guiana with sixteen other deputies. He would remain in exile at Sinnamary for over two years with several other deportees, including General Pichegru. Of the sixteen deported to Sinnamary, eight died there or while escaping, six escaped successfully, and two were finally recalled to France. De Ladebat returned to France in February 1800 after intervention from the First Consul, Napoléon Bonaparte. After his return, several "départements" asked him to represent them in the Senate. However, he remained suspicious of Bonaparte, who had always blamed him for denouncing previous acts of violence in Italy, and had demanded his dismissal shortly before the events of 18 Fructidor. Suspicious of his independence, Bonaparte removed de Ladebat's name from the Senate roles. De Ladebat was the only surviving member of the 18 Fructidor plot to leave politics and return to commerce. Explaining his abstention from politics, he wrote,  De Ladebat gained widespread recognition for financial competence and ability after taking over direction of the "Banque Territoriale" and organizing the final liquidation of the "Caisse d'Escompte", a predecessor of the Banque de France. He sought to repair the damage done to his finances following his deportation after 18 Fructidor; he reclaimed the remainder of his dispersed or confiscated assets and, notably, obtained compensation for the Sartine, one of his family-owned boats earlier requisitioned for use in the Indies. During the Bourbon Restoration, he fell out of favor with the House of Bourbon. He also contributed to the establishment of the Caisses d'Epargne and philanthropic institutions. In 1818, he became the president of the Protestant Society of Forethought and Mutual Assistance, and a member of the Society of Christian Morality. In 1821, he was among the founders of the Committee for the Abolition of Slavery, along with Auguste de Staël and Charles de Rémusat.