Dismantling Jus Soli

The principle of jus soli has been progressively dismantled in France through the tightening of conditions governing access to French nationality in Mayotte—the 101st department of the Republic and an archipelago in the Comoros located in the Indian Ocean. France does not recognize an absolute form of birthright citizenship. Birth on French soil does not in itself confer nationality. The acquisition of French nationality by birth is subject to legal conditions: a child born in France may acquire nationality if at least one parent was also born on French territory; if neither parent was born on the French soil, the child must have resided in France for at least five years since the age of 11 in order to automatically acquire French nationality at age 18, or by declaration from the age of 13.

In the case of Mayotte, the 2018 Immigration Law introduced an additional requirement. This restrictive approach was reinforced by the adoption, on 9 April 2025, of a new legislative measure—supported by the Government—designed to further limit access to birthright citizenship. The Conseil constitutionnel upheld the constitutionality of the contested provisions in its decision of 7 May 2025. This legislative sequence is striking given its temporal proximity to the humanitarian crisis affecting Mayotte as Cyclone Chido devastated the territory in December 2024. Nevertheless, both Parliament and Government chose to advance a securitarian agenda, focusing on the stigmatization of foreigners, rather than prioritizing the humanitarian needs of the archipelago population.

The Restriction of Jus Soli in Mayotte

In Mayotte, the acquisition of French nationality through jus soli was already constrained prior to the recent legislative reform. In general, to access nationality proof of five years’ residence in France is required. However, children born to foreign nationals often reside in informal settlements and do not possess required documentation.  This makes it difficult to establish continuous lawful residence with the effect of many children being excluded from jus soli.

The 2018 Immigration Law introduced an additional criterion specific to Mayotte: children born there to non-French parents may only acquire French nationality if, at the time of birth, at least one parent has been residing legally and continuously in France for a minimum of three months. This measure further restricted access to nationality. Subsequently, a legislative proposal initiated by the Les Républicains party sought to further tighten access to French nationality for children born in Mayotte. Justified as a means to combat irregular migration, the proposal originally required that both parents have been legally present in France for at least one year at the time of the child’s birth. The National Assembly amended the proposal to impose a more stringent condition: legal residence of both parents for a minimum of three years. However, in March, the Senate reverted to the initial one-year requirement. Ultimately, both chambers reached agreement in April on this latter version. The Conseil constitutionnel in its decision of 7 May 2025 upheld the constitutionality of the adopted provisions.

Nonetheless, the compatibility of this legislative text with the French Constitution remains questionable, as emphasized in the contribution extérieure submitted by Lisa Carayon and Serge Slama.

Notably, no impact assessment was conducted in relation to the implementation of the 2018 Immigration Law. The number of children acquiring French nationality through jus soli in Mayotte declined significantly from approximately 2,800 in 2018 to just 900 in 2022. However, the primary objective underpinning this restriction—the deterrence of irregular migration—has not been achieved. Yet this very goal drove the political agenda advanced by Les Républicains and later endorsed by Interior Minister, Bruno Retailleau, and Minister of Justice, Gérald Darmanin. The latter, while serving as Minister of the Interior in January 2024, proposed the complete abolition of jus soli in Mayotte.

The idea that restraining the access to French nationality serves to reduce migratory flows lacks evidentiary support. To date, no scientific study has established a causal link—or even a significant correlation—between nationality law and migratory flows. Accordingly, reforms aimed at restricting access to nationality appear unfounded. Indeed, despite the implementation of the 2018 law, arrivals of Comorian and sub-Saharan African nationals on Mayotte’s shores have continued unabated.

Moreover, the notion that a nationality restriction—whose effects would only be felt thirteen years after a child’s birth—could deter migration ignores the complex socio-historical realities of the region. Migration between the islands of the Comoros archipelago is deeply rooted in longstanding familial, cultural, and historical ties. Citizens of the Islamic Republic of the Comoros will continue to travel to Mayotte to reunite with family members and to escape a dire socio-economic situation. As for migrants arriving from continental Africa, many originate from the Great Lakes region, which includes several states known for producing refugees due to ongoing conflict and persecution. The decision to migrate to Mayotte is not determined by an eventual access to French nationality but rooted in “push factors.”

The Temptation to Suppress Jus Soli in Mayotte

In January 2024, then-Minister of the Interior Gérald Darmanin advocated for the abolition of jus soli in Mayotte, declaring that “it will no longer be possible to become French unless one is the child of a French parent.” His successor, current Interior Minister Bruno Retailleau, reiterated this position in February 2025. Within far-right political circles, the suppression of jus soli in Mayotte is viewed as a precursor to broader reforms aimed at dismantling jus soli nationwide. All this echoes the ideological discourse historically advanced by the far right, dating back to the leader of Action Française, Charles Maurras, whose doctrines continue to inform the ideological foundations of contemporary far-right positions in France.

The initial restriction of jus soli in Mayotte introduced by the 2018 Immigration Law was upheld by the Conseil constitutionnel in its decision of 6 September 2018. The Conseil relied on Article 73 of the French Constitution of 1958, which permits legislative adaptations in overseas departments in light of their “particular characteristics and constraints.” On this basis, the Conseil constitutionnel deemed the requirement of a three-month legal residence by one parent at the time of the child’s birth in Mayotte to be a permissible legislative adaptation to address the specific migratory pressures affecting the archipelago. The Conseil constitutionnel reaffirmed this reasoning in its 2025 decision concerning the 2025 legislative reform. It held that the prospect of acquiring French nationality could legitimately be regulated in a way that purportedly mitigates irregular migration flows into Mayotte.

Aside from the lack of evidentiary support for a link between restrictive nationality laws and a reduction in migratory flows, the Conseil’s reasoning suffers from two additional flaws.

First, the requirement that both parents must have legally resided in Mayotte for a period of one year at the time of the child’s birth cannot reasonably be regarded as a mere territorial adaptation of national law. Rather, it constitutes a substantive dismantling of the jus soli principle, going beyond what Article 73 of the Constitution allows.

Second, the reform raises legal questions under Article 1 of the French Constitution of 1958. By introducing differentiated access to nationality based solely on the territory of birth within the French Republic, the reform may infringe upon the principle of equality between children born on French soil—whether in Mayotte or elsewhere in France. Such differentiation also risks undermining the constitutional principle of the indivisibility of the Republic, effectively creating a distinction between the national territory as a whole and a single overseas department. A complete suppression of access to nationality for those born in Mayotte would take this even further. This would mark a regressive return to a colonial-era system, under which jus soli did not apply to children born there. That regime was only abolished in 1993 under a conservative government, prior to Mayotte’s accession to the status of a departmental collectivity.

What About Jus Soli in Metropolitan France?

The constitutional analysis would differ if the abolition of jus soli were extended to the entirety of French territory, including metropolitan France. While this would avoid violating the principle of the indivisibility of the Republic, it would remain highly questionable. The Conseil constitutionnel has never recognized jus soli as a constitutional principle, neither in its 1993 jurisprudence nor in its 2018 ruling. It has explicitly refused in 2025 to acknowledge jus soli as one of the “principes fondamentaux reconnus par les lois de la République” (fundamental principles recognized by the laws of the Republic).

This stance can be criticized. Although access to nationality for children born on French soil can be traced to practices under the Ancien Régime, jus soli can be regarded as a foundational element of the Republican legal tradition. It was reaffirmed during the Revolution and consolidated under successive French Republics. For one, the laws of 26 June 1889 and 10 August 1927 both enshrined jus soli. It has also been applied continuously and without substantial interruption across the national territory (with the exception of Mayotte prior to 1993) even during the Vichy regime. So it could be seen as a fundamental principle of the Republic, thus being part of the “bloc de constitutionnalité” and so benefitting from a constitutional value.

During deliberations on the legislative proposal, Prime Minister François Bayrou raised the prospect of initiating a broader national debate on the question: “What does it mean to be French?” Such a discussion is both concerning and misleading, particularly given that a similar public debate was already launched in 2009 under President Nicolas Sarkozy’s administration.

It is concerning as it amplifies rhetoric such as that of Interior Minister Bruno Retailleau, who explicitly linked migratory issues in Mayotte to the fact that most migrants are Black and Muslim. This rhetoric advances a racialized and exclusionary understanding of French nationality, and resonates with far-right slogans. This is fundamentally at odds with the constitutional values of the Republic and the social reality of France’s pluralistic citizenry.

It is misleading because it conflates two distinct concepts: nationality and citizenship. Nationality constitutes a legal bond between an individual and the State, conferring legal status and protection under international and domestic law. Citizenship, by contrast, refers to the set of political rights and duties associated with democratic participation. When the Prime Minister invoked “rights and duties” as central to French identity, he blurred this distinction, contributing to public confusion around the legal foundation of nationality law.

The foundational principles enshrined in the national motto—Liberty, Equality, Fraternity—should be sufficient to articulate what it means to be French, transcending distinctions of race, religion, and origin.

The Elephant in the Room

A fundamental question persists. Why is migration once again being framed as the central issue in Mayotte, when the priority should instead be the management of a severe humanitarian crisis caused by Cyclone Chido— a crisis that has been compounded by a prolonged water shortage, rising levels of delinquency, and escalating insecurity? Why is the government choosing to reopen a divisive national debate on the definition of French identity, rather than addressing the material and structural causes of the crisis?

As political theorist Benjamin Boudou has argued, such a posture may be explained by the instrumentalisation of migration as a policy diversion. What he terms the “migrantisation” of public policy refers to the tendency of political actors to attribute complex socio-economic failures to the presence of migrants, thereby deflecting attention from state responsibility and systemic dysfunctions. This dynamic is particularly visible in Mayotte—the poorest department of the French Republic—where the population is experiencing a marked deterioration in living conditions. Education, employment, healthcare, justice, housing, and inequality are the domains in urgent need of comprehensive policy engagement if the fabric of social cohesion is to be restored.

Rather than securitising nationality law and fuelling identity-based tensions, policymakers should refocus their efforts on the structural reforms required to uphold the principles of the French Republic.