The families of two babies swapped at birth 20 years ago are suing a maternity clinic for £10 million.
Sophie Serrano's baby Manon had jaundice, and at a day old she was put in an incubator next to another newborn, Melanie, with the same condition at a clinic in Cannes, France.
The babies were then returned to the wrong mothers, in neighbouring private rooms.
Both mothers immediately expressed doubt about the babies, pointing to their different hair lengths, but they were sent home anyway, according to French newspaper Nice Matin.
Ten years later, Manon's father did a paternity test because he was troubled by the fact his dark skinned daughter looked nothing like him.
It revealed he was not her biological father. Sophie Serrano then discovered she was not Manon's mother either.
This sparked an investigation to try and find the other family who had been handed their biological daughter.
The investigation revealed that at the time of the births in 1994, three newborns suffered from jaundice - the two girls and a boy - and the clinic only had two incubators with the special lights.
The girls were therefore put together in one incubator, according to the lawyer of one of the obstetricians being sued.
Another obstetrician, two paediatricians, the clinic and an auxiliary nurse are also being sued.
The two sets of parents eventually met their biological daughters for the first time when they were both 10 years old, but did not ask that they be switched back.
Ten years on, both families are suing for a total of more than €12m (£10 million).
The other family involved in the case also attended Tuesday's closed-doors court hearing but wants to remain anonymous.
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