"Balance between privacy and [national] security"
Yeah, right. The balance tipped away from privacy to "national security" (tracking, thoughtcrime, harassing polical opponents, etc.) at the advent of the information age. Before that, criminals put data beyond the reach of law enforcement all the time -- pretty sure fire, for instance, isn't all that new of an invention and that it works really well against incriminating papers. It's just that in the old days you actually had to bother tracking someone with real police work instead of just waiting to sift through mountains of data and cherry pick the crimes you wanted to prosecute without actually doing any work beforehand.
Nothing like making average law-abiding citizen's lives a bit more "exciting" (fending off identity thieves, having to prove innocence for crimes not committed, watching what you say and think in private), and also suppressing "unwanted public discussion", all for the sake of convenience when someone commits a crime, eh?
