The End of Miller’s Time: How Sensitivity Can Categorize Third-Party Data After Carpenter

For over 40 years, the Supreme Court has permittedgovernment investigators to warrantlessly collectinformation that citizens disclose to third-party serviceproviders. That third-party doctrine is under significantstrain in the modern, networked world. Yet scholarlyresponses typically fall into unhelpfully extreme camps,either championing an absolute version of the doctrineor calling for its abolition. In Carpenter v. UnitedStates, the Court suggested a middle road, holding thatsome categories of data—such as digital locationinformation collected from cell phones—do not neatlyfall into the third-party doctrine’s dichotomy betweenunprotected, disclosed information and protected,undisclosed information. But the majority elucidatedlittle rationale upon which to draw such nuanceddistinctions.This Article provides the missing rationale for suchcategorization: informational sensitivity. Disclosure to athird party matters but is not a trump card. Sensitivitymatters too. I thus propose a two-step test to determine ifthe government must obtain a warrant before collectinginformation from a third party. First, the Court shouldanalyze the information’s sensitivity, placing it on asensitivity continuum rather than a disclosuredichotomy. The Court can look to related jurisprudence,and the inherent meaning such information conveys, todetermine placement on that continuum. Second, if the information is sensitive, the Court should decidewhether the government has collected enough of it tocreate an informational mosaic of the citizen. If so, thatcollection is a search.The Court has long held that some data, like medicalrecords or phone conversations, are too sensitive to bewarrantlessly collected from third parties.Intermediately sensitive data, like the financialinformation in United States v. Miller and the cell sitelocation information in Carpenter, might bewarrantlessly collected in small amounts, but is toosensitive for warrantless collection in bulk. The Courtshould adjust the third-party doctrine to account forsuch sensitive information and craft provisional rules toprotect it. Doing so will enhance both the public’ssecurity and its regard for the Court