Brief of Amici Curiae of CEI, Cato, and Reason Foundation in Carpenter v. U.S.

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For nearly 40 years,[1] this Court and courts below have struggled with using a sociological method for interpreting the Fourth Amendment in difficult cases. They have asked whether government agents disturbed a “reasonable expectation of privacy,” reasoning backward from the answer to whether or not a “search” offensive to the Constitution has occurred.

That methodology has been difficult for courts to apply consistently, and in recent years this Court has used it less and less often as a decision rule. This Court should shed that sociological approach and adopt a juridical method for applying the Fourth Amendment. It should assess the facts of the case in terms of the law, encouraging lower courts to do the same.

Specifically, the Court should examine the following questions:

  • Was there a search?
  • Was there a seizure?
  • Was any search or seizure of “persons, houses, papers, [or] effects”?
  • Was any such search or seizure reasonable?

Using that simple and familiar legal methodology would allow this Court to address directly the challenging questions this case presents, including: When does a seizure of data occur? When does a search of data occur? When is data a constitutional “paper” or “effect”? Who has property rights in data sufficient to assert Fourth Amendment rights in it?

The government’s compulsory acquisition of data in this case was a seizure. Processing the data to make it human-readable was a search. The records were in relevant part the property of Messrs. Carpenter and Sanders, who enjoyed contractual rights and regulatory protections making them so. And digital documents are best treated as constitutional “papers” or “effects.”

That leaves the question whether it was reasonable for the government to seize and search them. There is a presumption in favor of the warrant requirement suggested by the text of the Fourth Amendment, and it is confirmed by this Court’s precedents. Thus, it was unreasonable to seize and search the data without a warrant. Lacking exigency or other excuse, the government should have gotten one.

The interests of Messrs. Carpenter and Sanders are not paramount to amici, of course. But as the importance of digital communications and data grows in society, the imperative to straightforwardly address their legal and constitutional status rises.

Without breaking from precedents, this Court can revise Fourth Amendment practice and determine when and how communications and data fit into the Fourth Amendment’s categories of protected things. Doing so would permit courts below to address seizures and searches of communications and data forthrightly, confidently assessing the reasonableness of such government action. Here, the result of that analysis calls for the Court to find in favor of the petitioner.

Read the full brief here.





[1] Katz v. United States, 389 U.S. 347 (1967), was decided on December 18, 1967.