They at least seem now to be rescinding those old name laws of theirs. Here's a PROMPT translation from the Legislation section of the French baby-name site:
http://meilleursprenoms.com/
The French legislation on the first names France restricted a long time the freedom of choice of the first names. During the Revolution, the French laws limited the range of choice of a first name to those of the calendar and the established list. (Law of Germinal 11th, the year XI). The first names which were not enough conformist had no luck(chance) to be accepted by the civil servants of State.
Law of Germinal 11th the year XI: " the used names in the various calendars, and those of the celebrities in the ancient(former) history can be only received, as first names, on state registers intended to notice the birth of the children; and it is forbidden to the public officers to admit it no other one in their acts. "
The ministerial Instruction of April 12th, 1966 marks the first stage towards the opening. This last one indeed admitted that " the force of the custom, in the material(subject), appreciably widened the limits initially assigned to the admissibility of the first names by the literal prescriptions of the law of Germinal 11th the year XI. "
The ministerial Instruction of April 12th, 1966 thus widens the directory of acceptable first names in first names pulled(fired) by the mythology, the régionnaux first names, the compound first names, tolerating even in certain cases diminutives and variations.
The order of the Court of Appeal of June 10th, 1981 follows close by the ministerial Instruction of April 12th, 1966 by deciding that " the relatives(parents) can notably choose as first names, under the general reserve that in interest of the child they are considered ridiculous, the used names in the various calendars and, while there is no official list of the authorized first names, he(it) does not there take place to require(demand) that the called calendar emanates from an official authority. "
But it is since 1993, with the Article 57 of the Civil code, (Titre II, chapter), that the law most considerably softened its legislation, guaranteeing virtually the acceptability of any first name.