By coincidence, see
https://www.bbc.co.uk/news/uk-47737635 on an ECHR ruling. Two highlights from the article:
- court's ruling means police can preventatively detain people even if they have no specific intelligence linking the individual to crime
- The judgement was significantly influenced by a decision in an unrelated football hooligan case from Denmark, which concluded that police could detain people - and therefore interfere with their right to liberty - if they believed it would prevent someone getting involved in later disorder.