The grandparents of two children, stranded in a refugee camp in Syrian Kurdistan along with their jihadist mother, want Paris condemned for its refusal to allow the three to return to France.
Lawyers for the grandparents claim that by deliberately refusing to repatriate the mother and her two children, all three sick, injured and extremely weak, France has deliberately exposed them to degrading and inhuman treatment, thus violating the European Convention of Human Rights.
The legal team also believes that another measure in the same convention guarantees that no national can be refused entry to the state of which he is a national. They will ask the European human rights tribunal to declare that the mother and her two children thus have an inalienable right to return to their own country.
The children are a three-year-old boy and his four-year-old sister. They were injured along with their mother in the battle for Baghouz, the last stronghold of Islamic State jihadists before it was taken by Kurdish-led forces.
They have been held for the last three months in the camp of Al-Hol in the northeast of the country where 73,000 people, including 12,000 foreigners are living, according to the United Nations.
The lawyers for the family say cholera, tuberculosis and dysentery are spreading in the camp.
The mother is targeted by an arrest warrant from a French anti-terror judge. But the family's lawyers says she "wants to see her children repatriated and assume her penal responsibility on French territory".
Other French families in similar situations have sought to bring relatives home using the French legal system, so far without success.
Paris refuses to accept the return of French jihadists who joined IS in Syria and Iraq and will take back their children only on a case-by-case basis.
Five orphaned children returned on 15 March and a three-year-old girl – whose mother has been sentenced to life imprisonment in Iraq – on 27 March.