&gt; If surveillance works, then Paris, Beirut, Bagdad et al wouldn&#x27;t have happed.<p>I don&#x27;t think surveillance is very good at preventing terrorism, but I think it could be useful to law enforcement after the fact to round up co-conspirators. I bet that once the identity of the Paris attackers was learned, the NSA pulled up a graph several levels deep of everybody they communicated it or associated with. It could very well help them figure out who else is involved and should be watched.<p>For the record, I&#x27;m opposed to surveillance and would be even if it were shown to be very effective. Privacy is important and is worth more than the lives that have been or will be lost to terrorists and other criminals.