Possession of one or more other nationalities did not, in principle, affect the French nationality. Section 23 of the Civil Code lays down the following principle:

Any adult person of French nationality, resid ant usually abroad, who voluntarily acquires a foreign nationality does not lose French nationality unless it is expressly declared, in accordance with Articles 26 et seq of this title.

However, under the Council of Europe, the Strasbourg Convention of 6 May 1963 established a mechanism for automatic loss of national origin in case of acquisition of the nationality of another Contracting State. Loses French nationality automatically, French major who voluntarily acquires the nationality of one of Other states are: Austria, Belgium, Denmark, Ireland, Italy, Luxembourg, Netherlands, Norway, Spain, Sweden and the UK (note that Portugal had signed but never ratified, and Spain has rejected immediately Chapter I of ratification on its reserves, keeping the Chapter II - service).

A protocol amending the Co nvention was signed in 1993 which reduced the scope of the Convention. This protocol, which is entered into force today between France, Italy and the Netherlands, enables the citizen of one of these three countries to retain their original nationality when they acquire the nationality of another signatory state of Protocol:

or when the person is born and is resident, or has been ordinarily resident for a period beginning before the age of 18,

or by virtue of their own free will following the wedding the person with a national of that State.

It's complicated enough, but it is not finished. The law passed on 24 Jul n July 2006 on immigration and integration has extended to four years duration of marriage prior to a declaration of nationality. But a statement contained in a letter from the Minister of Foreign Affairs e Does France's European, dated March 3, 2008, registered at the Secretariat General March 4, 2008, France = "_blank"> Denounced Chapter I of the Strasbourg Convention, effective March 5, 2009.

Furthermore, France does not distinguish between bi and the other French in terms of rights and duties related s citizenship. A French binational however, can not uphold his French nationality with the authorities of another State whose nationality he possesses also when residing on its territory, binational then generally being considered by the State as a national exclusive.

[Source: "Http://www.diplomatie.gouv.fr/fr/les-francais-etranger_1296/vos-droits-demarches_1395/nationalite-francaise_5301/nationalite-francaise_14144.html"
[19-01-2011]