Richard Posner (blog), a federal appeals judge in the 7th circuit, is on the warpath against civil liberties. His new book is destined to be the sort of thing that would make my blood boil. This New Republic article from January is a bit shorter. He repeats the falacy that the purpose of the 4th Amendment is merely to protect people from embarassment when the Government looks at their underwear, and so there is no privacy implication when robots pick your house apart for contraban.

Once a phone number in the United States was discovered to have been called by a terrorist suspect abroad, the NSA would probably want to conduct a computer search of all international calls to and from that local number for suspicious patterns or content. A computer search does not invade privacy or violate fisa, because a computer program is not a sentient being. But, if the program picked out a conversation that seemed likely to have intelligence value and an intelligence officer wanted to scrutinize it, he would come up against fisa's limitations. One can imagine an even broader surveillance program, in which all electronic communications were scanned by computers for suspicious messages

He does, however, make one suggestion that I have made before:

Permit surveillance intended to detect and prevent terrorist activity but flatly forbid the use of information gleaned by such surveillance for any purpose other than to protect national security.

Its hard to know how well this would work in practice, both because the program will identify serious crimes that don't rise to national security threats and cause a lot of moral teeth grinding on the part of the people involved, and because the definition of "national security threats" has risen to include "the radical fringe of the opposition political party" consistently in history. But, those caveats don't completely eliminate the possibility that there is something workable in this idea.

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