In short, the physical and legal barriers people place around their information define both their actual and “reasonable” expectations of privacy and should provide the doctrinal touchstone of the search warrant requirement. When one has arranged one’s affairs using physics and the law of property and contract to conceal information from preying eyes, government agents may not use surreptitious means and outré technologies like thermal imaging to defeat those arrangements without obtaining a warrant that conforms to the requirement of the Fourth Amendment. In Jones, the Court took an important step in this direction. It should now recognize the privacy of informational data that has in fact, in the words of the Fourth Amendment, been “secure[d]” by sufficient physical and legal protections.