Nabil Hadjarab, 33, has been held in Guantanamo without trial since 2002 after allegedly being sold to US troops while in hospital in Afghanistan following the 9/11 attacks on the US.
The American authorities cleared him for release in 2007 but he remains in the US prison camp in Cuba.
He began a hunger strike a month ago, telling his family he had lost all hope of ever being released.
He is now being force-fed.
On Friday his lawyer, Joseph Bréham, lodged a legal case to oblige the French government to allow Hadjarab to come to France, where he grew up.
All his family lives here.
"Nabil is one of about 100 detainees in Guantanamo who are not under investigation and are therefore considered innocent," Bréham told RFI. "And yet they’ve been detained for just over 11 years, with no hope of coming out … at least in the short term."
The procedure that Bréham hopes the court will authorise is "very rapid", the lawyer explains.
"The case will be pleaded by Monday at the latest," he says. "The aim is to force Manuel Valls as minister of the interior to agree to Nabil coming to France , to let him see his family, and let him lead a normal life once more."
Over 11,500 people have signed an online petition for Nabil Hadjarab's release.