A public or ministerial officer is a person holding an office awarded by the State and appointed by decision of a minister. Appeal court process servers, bailiffs, notaries, Council of State or Court of Cassation lawyers are all ministerial officers. Some of the above are also public officers endowed with the power of authenticating legal or judicial deeds and of enforcing the decisions of the justice system (such is the case of notaries, bailiffs...).
Source : ministère de la Justice (site : http://justice.gouv.fr)