Lawfare: The Best Way to Rule for Carpenter (Or, How to Expand Fourth Amendment Protections Without Making A Mess)

Lawfare: The Best Way to Rule for Carpenter (Or, How to Expand Fourth Amendment Protections Without Making A Mess) by Orin Kerr:

Last month, the Supreme Court held argument in Carpenter v. United States, the pending case on whether the Fourth Amendment protects cell-site records. There seemed to be at least five votes sympathetic to ruling for Carpenter. At the same time, there was very little agreement about how to get there. What line should the Court draw, and based on what rationale? No clear answers emerged.

In this post, I want to identify what I think is the best way to rule for Carpenter. To be clear, I don’t think this approach is the best way to rule. My amicus brief explains why I think cell phone users have no Fourth Amendment rights in their historical cell-site records. But if the Court wants to go the other way, there are better and worse ways to do that. This post identifies what I think is the best way to rule for Carpenter that would cause the fewest headaches going forward. To put it in law clerk terms, this is the thinking you do when your judge tells you, “Thanks very much for sharing your views. Now write it the other way.”

Here’s my bottom line: If the Court wants to rule for Carpenter, it should hold that individuals have Fourth Amendment rights in records solely useful to the government to identify that individual’s physical location. In the language of modern Fourth Amendment law, government collection of location records, the sole government function of which is to reveal a person’s physical location, infringes that person’s reasonable expectation of privacy.