Seven French health officials have gone on trial in Paris, charged over the deaths of more than 100 children from the human form of mad cow disease.
The children had all been injected with growth hormones taken from potentially infected human corpses in the 1980s.
The seven are accused of hiding the dangers of the treatment from the parents and breaching safety rules.
All seven deny the charges but face up to 10 years' jail if found guilty. The trial is expected to last four months.
The first victim of Creutzfeldt-Jakob Disease (CJD), the human form of mad cow disease, died 16 years ago.
Experts say it is likely that other children who underwent the treatment will also fall victim to the disease in the coming years.
Prosecutors say the medical staff gathered hormones from the pituitary glands of corpses in hospitals which specialised in infectious diseases and even neurological disorders, and were possibly infected with CJD.
'No warning'
In the early 1980s, 14 countries, including the UK and the US, banned the extraction of hormones from pituitary glands after the death of a young American suggested a possible link with CJD. But France continued with the old method until 1988, while parents were not warned of a potential risk, prosecutors say.
"We feel deeply moved. It is as if our children were here watching us," said Jeanne Goerrian, president of a victims' association and one of 200 civil plaintiffs in the case.
"This is not victory yet. It is an important stage in the fight. We hope justice will be done in memory of our children."
Defence lawyers for the accused, who are now mostly in their 70s and 80s, say their clients acted in good faith, armed with the medical knowledge of their time.
"Twenty years ago, how much was really known?" said defence lawyer Benoit Chabert.
French medics sued in CJD scandal
Moderators: Alyrium Denryle, Edi, K. A. Pital
French medics sued in CJD scandal
BBC