Related Rule
France
Practice Relating to Rule 100. Fair Trial Guarantees
France’s Disciplinary Regulations (1975), as amended, provides that it is prohibited to “convict persons without a previous judgment pronounced by a regularly constituted tribunal affording judicial guarantees provided by law”. 
France, Règlement de Discipline Générale dans les Armées, Decree No. 75-675 of 28 July 1975, replacing Decree No. 66-749, completed by Decree of 11 October 1978, implemented by Instruction No. 52000/DEF/C/5 of 10 December 1979, and modified by Decree of 12 July 1982, Ministère de la Défense, Etat-Major de l’Armée de Terre, Bureau Emploi, Article 9 bis (2).
France’s LOAC Summary Note (1992) provides: “Every person, whether combatant or non-combatant, shall benefit from the fundamental judicial guarantees.” 
France, Fiche de Synthèse sur les Règles Applicables dans les Conflits Armés, Note No. 432/DEF/EMA/OL.2/NP, Général de Corps d’Armée Voinot (pour l’Amiral Lanxade, Chef d’Etat-major des Armées), 1992, § III.
The Summary Note further states that “deprivation of the fundamental judicial guarantees” is a grave breach of the 1949 Geneva Convention III. 
France, Fiche de Synthèse sur les Règles Applicables dans les Conflits Armés, Note No. 432/DEF/EMA/OL.2/NP, Général de Corps d’Armée Voinot (pour l’Amiral Lanxade, Chef d’Etat-major des Armées), 1992, § 3.4.
France’s LOAC Teaching Note (2000) states that “violations of the fundamental judicial guarantees” are grave breaches of the law of armed conflict. 
France, Fiche didactique relative au droit des conflits armés, Directive of the Ministry of Defence, 4 January 2000, annexed to the Directive No. 147 of the Ministry of Defence of 4 January 2000, p. 7.
France’s LOAC Manual (2001) states that one of the three main principles common to IHL and human rights is the “principle of inviolability” which guarantees to every human being the fundamental judicial guarantees. 
France, Manuel de droit des conflits armés, Ministère de la Défense, Direction des Affaires Juridiques, Sous-Direction du droit international humanitaire et du droit européen, Bureau du droit des conflits armés, 2001, p. 52.
The manual refers to common Article 3 of the 1949 Geneva Conventions and stipulates that the “passing of sentences … without previous judgment pronounced by a regularly constituted court affording all the judicial guarantees which are recognized as indispensable by civilized peoples” is prohibited. 
France, Manuel de droit des conflits armés, Ministère de la Défense, Direction des Affaires Juridiques, Sous-Direction du droit international humanitaire et du droit européen, Bureau du droit des conflits armés, 2001, p. 101.
France’s Code of Defence (2004), as amended in 2008, states: “Members of the military shall respect the right to a fair trial of those persons suspected of committing crimes or offences.” 
France, Code of Defence, 2004, as amended in 2008, Article D4122-9.
The instructions given to the French armed forces for the conduct of Opération Mistral, simulating a military operation under the right of self-defence or a mandate of the UN Security Council, state: “Every person has the right to a fair trial by a regularly constituted tribunal respecting the fundamental judicial guarantees.” 
France, Etat-major de la Force d’Action Rapide, Ordres pour l’Opération Mistral, 1995, Section 6, § 64.
France’s Penal Code (1992), as amended in 2010, states in its section on war crimes related to international armed conflict:
Hindering the right of a person protected by the international law of armed conflict to be regularly and impartially tried, in accordance with the provisions of the applicable international conventions, is punishable by 20 years’ imprisonment. 
France, Penal Code, 1992, as amended in 2010, Article 461-21.
In its section on war crimes related to non-international armed conflict, the Penal Code states:
Passing sentences and carrying out executions without previous judgment pronounced by a regularly constituted court, affording all judicial guaranties provided for under the 1949 Geneva Conventions and their [1977] Additional Protocols is punishable by 20 years’ imprisonment. 
France, Penal Code, 1992, as amended in 2010, Article 461-31.
In 2008, in the “Disappeared of the Beach” case, France’s Criminal Chamber of the Court of Cassation held:
[T]he universal jurisdiction clause, based on the presence in France of the supposed perpetrator of an offence which is likely to fall within the provisions of the New York Convention [1984 Convention against Torture and Other Cruel, Inhuman and Degrading Treatment or Punishment] … is strict and cannot be extended to the situation where the interested person has domicile or residence in France but where the condition of physical presence of this person at the commencement of the proceedings is not satisfied. 
France, Court of Cassation (Criminal Chamber), “Disappeared of the Beach” case, Judgment, 9 April 2008, p. 9.
In 2008, in the “Disappeared of the Beach” case, France’s Criminal Chamber of the Court of Cassation held:
[T]he domestic judge, when he receives a case based on a universal jurisdiction clause, shall ensure that the res judicata which took place abroad does not hinder the prosecution in France. … This assessment, which is a condition to the legality of the public prosecution, shall be effective and take place in the preparatory phase of the criminal proceedings established in France … If the investigating chamber fails to proceed with such assessment, the interested parties shall benefit, without discrimination, of a useful and effective remedy to hinder the commencement of the public prosecution. 
France, Court of Cassation (Criminal Chamber), “Disappeared of the Beach” case, Judgment, 9 April 2008, p. 7.