It may be an abuse of the law, but the fact is that it is common practice. First result on google: https://crabgrass.riseup.net/assets/138965/120313+manifestan

It may be an abuse of the law, but the fact is that it is common practice. First result on google: https://crabgrass.riseup.net/assets/138965/120313+manifestant+refus+ADN+relaxe.pdf https://crabgrass.riseup.net/assets/138965/120313+manifestan... Giorgos, militant anarchiste, avait été placé en garde à vue lors d’une manifestation à Montpellier en octobre 2010. Il avait été accusé par les policiers d'avoir, avec d'autres manifestants, renversé des poubelles. Une poursuite classée sans suite pour cause d’« infraction insuffisamment caractérisée ». Mais il avait eu le tort de refuser qu’on lui prélève ses empreintes génétiques et a été condamné en première instance à un mois de prison avec sursis par le tribunal correctionnel de Montpellier. Translation: Giorgos, an anarchist militant, was arrested during a demonstration in Montpellier in Oct 2010. He was accused by the police, along with other demonstrators, to have knocked over bins. The case was dismissed because the offense "was insufficiently characterized". But his fault was to refuse to have his DNA taken and was sentenced for that to a month of suspended jail term by the Montpellier court. I read similar stories in other demonstrations.