For more than forty years, electronic surveillance law in the United States has drawn a strong distinction between the protections afforded to communications "content"and those afforded to the "noncontent"—also known as "metadata"—associated with it. The legal framework for surveillance law was developed largely in the context of the mid-twentieth century telephone system, which itself treated content and metadata as cleanly distinct technical concepts. In an era of relative stability in telephone services and technologies, the constitutional and statutory legal principles, once established, were usually straightforward to apply to individual cases, even as the technology incrementally improved. The Internet, a great disrupter in so many ways, challenges bedrock assumptions on which several principles of modern surveillance law rest...
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