Historically French citizenship law was mainly based on the principle of ius soli. Citizenship in France can also be acquired by birth where a new child is born to at least one French national. Citizenship can also be acquired by marriage to a French national and by naturalisation after at least five years of habitual residence in France.
In French citizenship law there is no legal text in relation to the acceptance or otherwise of dual citizenship. This is tolerated by French authorities, in relationship to the bilateral agreements between France and the original country of citizenship.
The possession of one or more nationalities does not, in principle, affect French nationality. France denounced Chapter I of the Council of Europe Convention of 6 May 1963 on the Reduction of Cases of Multiple Nationality and on Military Obligations in Case of Multiple Nationalities. This denunciation took effect on 5 March 2009.
A French national who acquires a new citizenship, has no obligation to declare to the French administration such acquisition. A foreign national applying for French nationality, should declare the original citizenship he holds on the French nationality request and the citizenship which he would like to renounce (if the case).