As others have mentioned, context matters a lot. The arrested group came back from Syria (where they fought alongside YPG against ISIS) radicalised, and were monitored ever since then. Their alleged crime isn't using Signal, it's just that a French anti-terrorism law allows to be arrested for "organisation with the intent to commit terrorist acts", which the DGSI(internal intelligence services) claims a radicalised g…
> As others have mentioned, context matters a lot. No, it does not. While this group is indeed suspicious, detaining them without a proof (and using whatsapp as your proof) opens a serious precedent. Now anyone can be detain for that. And it'll be used for serious suspicious cases later but also will be used against someone like you because someone in the police didn't like how you walk.
Of note for US readers, France legal system is not a jurisprudential system as in the US. That is, a judge's ruling does not become law - i.e must be followed as law by another judge -, only parliament can make law.
The only instance having a form of jurisprudence power is Cour de Cassation, but that's only indirect: being the ultimate instance of recourse CCass rulings for similar cases have high chances of having similar outcomes. They may (or may not) influence other court rulings but a) they are not law and b) reaching to CCass is not guaranteed, so other courts judges are completely free to rule differently (as long as they abide by law)
That said, holistically these precedents matter as they may give broad strokes on mindset trends from the powers at play.