Any attempt to interfere with such rights must at least have some prospect of achieving the desired objective although I'd be inclined to replace his use of the verb 'would' with 'could' (have prevented the incident).

Well, if you make that replacement (with which I agree), you change the standard significantly. My point was that since no law can guarantee someone won't break it (or at least try to), using that as a standard for drafting the legislation in the first place isn't terribly realistic =)

I do agree that passing a law that doesn't have at least a reasonable chance of achieving its purpose is a complete waste of time ...