According to the Cour de Cassation, it is not necessary to show reliable and certain vital records in order to obtain French nationality by « possession d’état »
In a judgment dated June 18, 20251, the French Cour de cassation (French highest civil and criminal Court) ruled that a person wishing to obtain French nationality under article 21-13 of the French civil code, i.e., on the basis of uninterrupted French « possession d’état » during the ten years preceding the application (as evidenced by possession of French passports, French national cards, etc.), was not required to prove certain and reliable vital records.
In principle, anyone wishing to obtain French nationality, whatever the mean, must provide certificates related to her/his civil status (for example birth and marriage certificates) that are certain, reliable and coherent with themselves and each other. The purpose of this principle is to ensure that individuals who obtain French nationality can receive a French birth certificate stating their surname, first name, gender, date and place of birth, and parentage, in accordance with article 98 of the French civil code.
For example, in the case that gave rise to the judgment of the Cour de cassation on June 18, 2025, the applicant submitted two of his own birth certificates mentioning different maternity hospitals as the place of birth. This discrepancy can give rise to legitimate suspicions that at least one of these certificates, or both, is irregular. Consequently, the applicant’s vital records are not considered reliable and certain, and in principle he should not be able to acquire French nationality.
The Cour de cassation nevertheless emphasized that the French naturalization by « possession d’état » pursuant to article 21-13 of the French civil code is subject to a special regime, since it arises from a factual situation.
Indeed, this mean of becoming a French citizen applies to individuals who have behaved as French citizens, and have been mistakenly considered as such by the French authorities for 10 years, as demonstrated by the submission of copies of French passports, French national cards, voter registration cards, etc.
In general, French naturalizations by declaration follow the establishment of valid civil status documents, for example for persons adopted by a French citizen, married to a French citizen, or born in France. In the latter cases, it is reasonable to require applicants to provide proof of reliable and certain vital records.
However, article 21-13 of the French civil code only requires proof of a factual situation, namely French « possession d’état » for 10 years. This is why the Cour de cassation considered that the requirement for reliable and certain vital records would have been an additional condition, not provided for by law, and therefore irregular.