When French philosopher Elizabeth Badinter denounced the use of the word “Islamophobia” on France Inter radio two weeks ago, calling it a tool to silence critics of religion, the watchdog’s rapporteur Nicolas Cadène issued a sharp rebuke.
"Three years-worth of educational work destroyed by one person in one interview", he tweeted. "Personally, I have never been called an "Islamophobe" whilst defending secularism."
Cadène's criticism of Badinter revived tensions within the Observatoire de la laïcité, several of whose members are at odds with the approach to secularism of both Cadène's and its president Jean-Louis Bianco.
Four of them have resigned in protest and have spoken out against what they see as an understanding of state secularism that seeks to accommodate religion by defending it against its critics.
But the debate goes back further.
Following the November attacks in Paris, Cadène and Bianco signed an appeal entitled "We are united", among whose 40 signatories were groups and individuals alleged to be close to the Muslim Brotherhood.
The centrist Senator Hugues Portelli, who has just stepped down in protest, says the disagreement within the Observatoire prevent it from functioning as an advisory comittee:
"There have been important quarrels about our conception of secularism and about its members positions, namely its president's, whether we can take position alongside so-called moderate Islamist groups," he said.
As for the legitimacy of the term "Islamophobia", which some intellectuals such as Badinter have questioned, Portelli says "its just a word to create polemics".
The controversy became even more bitter on Monday when Valls got involved, despite the Observatoire's independent status.
At a meeting organised by the Jewish umbrella group CRrif, Valls lashed out at Jean-Louis Bianco, saying it was unacceptable for the representatives of a public institution to criticise a public figure who has always fought for secularism, such as Badinter.
Valls paid tribute to her “uncompromising defense of secularism” and said he supported the philosopher’s position.
Jean Glavany, who was one of the first members of the Observatoire to quit in protest, explained to RFI that there have always been two tendencies within the French left.
“On the one hand French secularism is about respecting differences and on the other it’s about overcoming them”, he says.
“I think the Observatoire was wrong in turning one faction against the other. That’s what the prime minister wanted to put an end to, and he was right.”
In response to the criticism, Cadène has insisted that both his tweet about Badinter and his signing of the controversial appeal were the expression of his and Jean-Louis Bianco's personal opinions and need not reflect the Observatoire's position on secularism.
“In its basic principles and understanding of secularism,” he added, “the institution is in full agreement – that’s why its members have all signed the Observatoire’s charter, unanimously.”
Jean-Louis Bianco defended Cadène in Le Monde on Tuesday, saying his tweet was not a personal attack on Badinter but simply an expression of opinion.
He also defended the opinion column he co-signed with Cadène, praising a "wonderful opportunity for the Republic".
"Amongst the many signatories, you'll find the great rabbi of France, several trade unions, the representative of the French Muslims... I think it's a shame that the Prime Minister didn't lool at the reality of the text."
The question remains whether an institution riddled with internal quarrels about its own principles can fulfil its function as an advisory body.
Whereas its president and its rapporteur insist on the legitimacy of its mission, dissident members Portelli and Glavany say the disagreements have compromised its goals.
Bianco can still count on the support of President François Hollande but he faces growing protests from public figures and social network users.
A regional president of the Observatoire in the Val d'Oise, Laurence Marchand-Taillade, has already launched a petition demanding his resignation.