France
Practice Relating to the Use of Prohibited Weapons
France’s Penal Code (1992), as amended in 2010, states in its section on war crimes related to international armed conflict:
[The following offences] are punishable by life imprisonment: … [e]mploying weapons, projectiles, materials or methods of warfare which are the subject of a comprehensive prohibition and are included in an annex to the Statute of the International Criminal Court accepted by France. 
France, Penal Code, 1992, as amended in 2010, Article 461-23.