So the obvious question about the newly disclosed NSA telephone database is whether or not it is legal.
Orin Kerr has a series of postings at his blog with analysis of this question. I do have a few fundamental differences with Orin's analysis, and his analysis is spread across three postings (first, second, third), so I thought I'd do my own summary of the situation.
Anyone who really wants to dig into the complexity here should probably also read Orin's analysis, since he goes into more detail on various points.
But here goes ...