The problem for engineers is that what lawyers call metadata does not track the application/transport/Internet/link layer model we all know and love. A good rul

The problem for engineers is that what lawyers call metadata does not track the application/transport/Internet/link layer model we all know and love. A good rule of thumb is that unless it's in the body of a message and maybe a Subject: line, DOJ argues it's not content. URLs could go either way. Re: Internet search terms, later in my article I try to address that: Whether the FBI believes its port reader software should be able to capture Subject: lines, URLs that can reveal search terms, Facebook "likes" and Google+ "+1s," and so on remains ambiguous, and the bureau declined to elaborate this week. The Justice Department's 2009 manual (PDF) requires "prior consultation" with the Computer Crime and Intellectual Property Section before prosecutors use a pen register to "collect all or part of a URL."