President Francois Hollande's call for convicted French-born terrorists to lose their citizenship if they have a second nationality has triggered uproar among those who see him adopting right-wing ideas that recall dark moments in France's history. Ever since the French Revolution in the late 1700s, "le droit du sol" ("the right of the soil") has been a fundamental principle, giving everyone born in the country the right to citizenship.
But in the aftermath of November's jihadist attacks in Paris, Hollande announced to an extraordinary session of both houses of parliament that he would seek changes to the constitution so that dual nationals - even those born in France - could be stripped of their French passport. The idea has huge support from a jittery nation, with nearly 90 percent backing the measure in a poll for BFM TV.
Hollande's Socialist government has staunchly defended the move with Prime Minister Manuel Valls saying the measure was already used in several Western countries including Britain, Canada and the Netherlands. "Removing French nationality from those who blindly kill other French in the name of an ideology of terror is a strong symbolic act against those who have excluded themselves from the national community," Valls wrote on Facebook.
But experts say the measure has little chance of deterring jihadists who are often willing to give up their lives, let alone their passports. And it could encourage the idea that dual nationals are more of a threat than other citizens - a particular problem in a country that has struggled to integrate immigrants.
"It introduces the idea of a different penalty for the same act, just because of the random chance of their birth," said Patrick Weil, a political scientist who met Hollande and advised him against the decision. Weil said France would become "the first democracy in the world" to enshrine in its constitution the principle of unequal treatment of dual nationals.
"The constitution is a text that is written to unify the people and this does the opposite. People know that reinforcing the cohesion of the nation is, in the long term, the only way to defeat terrorism, and this proposal creates an immediate division in the country," he said. As well as breaking a legal principle, the measure also touches a raw nerve in France's history, say critics. The Vichy regime, which collaborated with the Nazis in the 1940s, stripped thousands of Jews and foreigners of French citizenship during World War II.
Dissenters in Hollande's Socialist party see the move as little short of ideological treason, not least since immigration was one of the few areas where there was clear daylight between the two mainstream parties. When right-wing leader Nicolas Sarkozy raised the idea of removing the "droit du sol" from some violent criminals in 2011, he was blasted by the Socialists.
Worse still in the eyes of the left, it was an idea first mooted by the far-right, anti-immigrant National Front (FN). "In wanting to steal the thunder of the far right, we risk implementing their programme," said Cecile Duflot, a former minister in Hollande's government.