Plenty of children have killed without first having been held in a specialised institution. They usually get put in such places after their most serious crime, not before. Prior to killing someone, they have generally not been absolute paragons of good behaviour. This is the information the head of the school has access to as they decide who is to be permitted on an excursion into a public place and who is not.
The several shoplifting children from the same school three years in a row, the child hurling stones at visitors in a park, the child holding someone up in the street at knifepoint and the child-stroke-young adult who was arrested for attempted murder in a local pub, all attending the same language school in the UK, were travelling with various group leaders who were cooperating with the educational institutions arranging the overseas trips. The idea that nobody beforehand had ever noticed anything amiss with their behaviour would stretch credibility to breaking point.
When it comes to school trips, educating children and responsible behaviour towards the public meet.
The Russian police were found to have violated human rights because, after finding relatively low-level cases of domestic violence, they failed to prevent higher levels of it as they did not adopt a zero-tolerance approach. When a school lets someone loose on the public, after having first seen evidence that their behaviour shows some sign of danger to another person, by the ECHR's logic this would be a human-rights violation, rather than merely irresponsible management of children.
Unlike the way individual countries create their laws, the ECHR sets a precedent which can then be applied to further cases. I suggest that, unless they overturn their ruling on Russia, there is going to be an avalanche of claims directed against schools by injured parties, to say nothing of what various therapists will be summoned to explain.
