Higher Education (Freedom of Speech) Bill

When the police decide to intervene, it is often not because a host organisation decides that they should or invites them to. They make a judgment, as constables, as to what would constitute a way of securing a peaceful circumstance for the event or for the premises. Nobody knows that it is going to happen unless they decide to do it, and nobody decides who is going to pay for it in advance, but happen it does, and arguments about who should then pay for it occur. How would a code of practice deal with that?