And can anyone explain how this prevents rape?
Let's say that the authorities think Bob is a potential rapist. Rape convictions are difficult to achieve, because many rapists fall back on the 'it was consensual' defence, which is difficult to disprove beyond reasonable doubt.
If they have this order against them they don't need to be convicted of rape to be imprisoned, they can be prosecuted for breaking the court order which doesn't care if the sex they have is consensual or not - just having sex at all without pre-warning the authorities is a criminal offences.
It's a way to get rapists off the street, to improve conviction rates for sexual offences (by lowering the threshold considerably) - it's only going to prevent rapes in those instances where the individual is self-aware enough to realise how vulnerable to imprisonment they are in the event of an accusation.
O.