security vs. privacy

This morning, I was listening to "Common Sense with Dan Carlin". Today's topic is called "the big snoop show ", which is concerned with how government surveillance such as recording phone conversation in the name of national security intrude civilian privacy. This is an interesting connection between security and privacy. While I have already accepted that we should distinguish between security and privacy (believe it or not, in computer science arena, the line between these two concepts tend to blur), I never thought privacy sometimes can be traded off for security.