1/ Is Carpenter the 1st Supreme Court majority opinion recognizing a 4th Amendment right completely unrelated to a search or seizure of a “person, house, paper, or effect”?
2/ Here’s my thinking. Off the top of my head, every search the Supreme Court has recognized before was ultimately of a person house paper or effect, even if phrased using the reasonable expectation of privacy language.
3/ Katz — phone booth as temp effect. Kyllo— home. Karo— home. Bond— luggage as effect. Terry frisk— person. Ex party Jackson— papers. Curtilage cases— home. Car searches— effects. Etc.
4/ But in Carpenter, the reasoning doesn’t seem to hinge on whether a person, House, paper or effect was searched. The key issue is just whether govt learned the whole (or enough of the whole to count) of a person’s physical movements.
5/ The counterargument would be that maybe the records were Carpenter’s papers. But the reasoning of Carpenter seems counter to that: any surveillance that collected the totality of physical movements is a search, and just no diff rule b/c happened to involve records.
6/ A key difference, I think, is that Carpenter is based on a reasonable expectation of privacy in a collective set of facts in the abstract (a person’s location over time) not the traditional focus of an REP in a place or thing. Learn enough facts= search. That’s new, it seems.
7/ I realize some argued that Katz itself did this, but I don't think that's right. More on my view here, on why Katz is readily reconciled with the Fourth Amendment's text. reason.com/volokh/2017/12… 
8) If I'm right, Carpenter opens up a new kind of Fourth Amendment claim: That the government learned some however-defined collectively private set of facts, and that independently of how it was collected, it is therefore a search. It's an REP in information, not a place/thing.
9) That's a change, I think. An example: When I teach the 4A, after I introduce the REP test -- based on what society "is prepared to recognize," the cases say -- I ask my students if they have an REP in a bunch of different cases. Most of them are places and things. Then,
10) to see how they react, I add this question: Do you have a reasonable expectation of privacy in your GPA? You can see students react in confusion to the question, because it's different; it's not privacy in a place or thing, but in a fact. In the past, I have later emphasized
11) that it was a sort of trick question: The 4A is about the places and things the police search, not about acquiring info in the abstract. But after Carpenter, I'm not sure I can say that. Maybe there are facts out there -- what facts, defined in what way, we don't yet know --
12) in which a person does have a reasonable expectation of privacy in the abstract. Of course, maybe a limit on all of this is that Carpenter is about equilibrium-adjustment -- that is, the government having new tech powers to learn what it couldn't learn before. To have that,
13) it's plausible to say that you would need to have (a) information that existed before but wasn't collectable in a practical way and also (b) a new technology that allows the government to collect that information easily. In that sense, Carpenter could only apply to a pretty
14) narrow category of facts: old-fashioned existing kinds of Information (like physical location over time) that couldn't be collected easily before but can be collected now through technology. That could still be a significant category of facts -- does using facial recognition
15) software to find a matching photo count? -- but you can't just come up with an set of facts, call them private, and say that the government conducts a search if they learn it. /end
