The trial began Monday, Radio France Internationale reported. Six people associated with L'Arche de Zoe have been charged with trying to arrange French adoptions for 103 Chadian children.
Two defendants, Eric Breteau, the group's former chairman, and his partner, Emilie Lelouch, are now living in South Africa and have said they have no plans to come to France. Breteau now operates a guest house, while Lelouch is running a circus, RFI said.
Philippe Van Winkelberg, who was the group's doctor, logistics organizer Alain Peligat, Agnes Peleran, a journalist, and Christophe Letien, who prosecutors say functioned as Arche de Zoe treasurer and remained in France, are in the courtroom.
Members of the group were convicted in Chad and given prison terms and fines. They were sent to France to serve their sentences and received pardons in 2008 from the president of France.
The current trial involves violations of French law.
Citane Ferrer, who wanted to adopt one of the supposed Darfur orphans, said she and other potential adoptive parents were told the group hoped to save a total of 1,000 children.
Members of the group were arrested in 2007 at an airport in eastern Chad. Police said they had 103 children with them, many of them wearing fake bandages covering supposed war injuries.