British police scuffled with protesters outside Parliament on Saturday as they arrested more than 400 demonstrators who gathered to defy a ban on the group Palestine Action, which the government labels a terrorist organization. Defend Our Juries, the campaign group organizing the protest, said 1,500 people took part in the London demonstration, sitting down and holding signs reading. “I oppose genocide, I support Palestine Action.” Within minutes, police began arresting the demonstrators, as bystanders chanted, “Shame on you,” and “Met Police, pick a side, justice or genocide.” There were some scuffles and angry exchanges as officers dragged away demonstrators who...