Sorry yes I do mean that sometimes you might need to act before someone commits crimes: thinking specifically of people who are in a state which makes then dangerous to others. In some cases you can reduce that risk without such measures, but not always.

As I say I have no idea whether I think this law *actually* does more harm than good, and my gut feeling is that I'd need to know a lot more about how it's actually used in practice before I could decide. There are other things which worry me much more.