The British government’s decision to ban a pro-Palestinian protest group as a terrorist organization was ruled unlawful on Friday by senior judges. The decision is a setback for the government of Prime Minister Keir Starmer, which has faced significant criticism over the ban and its implications for free speech and the right to protest. The ruling in Britain’s High Court could still be appealed, however. The group, Palestine Action, does not promote violence against individuals. But its members have damaged facilities linked to an Israeli weapons manufacturer and last June broke into R.A.F. Brize Norton, Britain’s largest air force base,...