What does a search warrant for an email get you? It doesn’t get you an email — an email isn’t a physical object. What it gets you is access to the server where the email “lives.” Does it matter, then, where the server is located? Are some servers, and the emails in them, outside the reach of U.S. law?

Those are the hard questions confronting the 2nd U.S. Circuit Court of Appeals in United States v. Microsoft Corp. As arcane as it may sound, the case has a great deal to tell us about the tech sector’s views on privacy and surveillance — and about the ways the landscape of privacy law may be about to change irrevocably.