The Volokh Conspiracy
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Over at Lawfare, I have a post up, "Relative vs. Absolute Approaches to the Content/Metadata Line," about a recently declassified decision by the Foreign Intelligence Surveillance Court of Review (FISCR). It begins:
One of the foundational questions in surveillance law is how to distinguish between the contents of communications and non-content metadata. Contents generally receive very high privacy protection, while metadata generally receive very low protection. Identifying the line between the two is critical. Earlier this week, the ODNI declassified an April 2016 FISCR decision on post-cut-through digits that adopts an approach to the distinction in some tension with a recent Third Circuit case. This post will explain the problem and the apparent disagreement.
First, some background. Communications networks are ways of sending messages from one party to another. For every message sent, there will be the substance of the message (the contents) and information about the message (metadata). At first blush, the distinction looks simple. In the case of a postal letter, the contents are the letter itself; the metadata are the information on the outside of the envelope. In the case of a phone call, the contents are the actual sound on the call; the metadata are the numbers dialed and times of the call.
But matters aren't so simple in part because messages are often passed on among parties. A might send a letter to B with instructions to contact C. D might call E and ask E to connect his call to F. The ability to pass on messages raises an important question: If a party receives a message directing the party to send on another communication or take some act, is that message contents or is it metadata?
There are two ways to look at it, which I will label the relative approach and the absolute approach. Under the relative approach, messages don't have an abstract status as contents or metadata. To classify a particular message, you look to the specific context in which the message was obtained and you ask whether the message was contents with respect to a communication between those two parties. Imagine A sends a message to B directing B to contact C and that C does so. Under the relative approach, the message was the contents of the communication between A and B but metadata of the communication between B and C. That is, A communicated the message to B, so it was the content of that message, while B then acted on the message and contacted C, which was metadata for the contact from B to C. Under the absolute approach, by contrast, you would devise a single answer. You might say that because the message was for B to contact C, and the fact of contacting C is metadata, then the message should be classified as metadata and contains no contents.
As the post explains, the Third Circuit and the FISCR have recently divided on the question. The Third Circuit adopted the relative approach, and the FISCR adopted the absolute approach. Check out the Lawfare post for the details.