Digital and Location Data

Digital and Location Data

The warrant framework in the preceding sections was built around physical things, such as papers in a desk or a weapon in a closet, and the question here is whether the same framework governs records held in a phone company's database or on a hard drive. It does, and the analysis moves through four points in this order: how Rule 41 defines property, what privacy interest attaches to historical location records, how stored data on a seized device is treated, and which Rule 41 provisions were written specifically for tracking devices and remote access. The Fourth Amendment decision that anchors the location-record point is taught on its own terms elsewhere, so only the part of its holding that matters for warrant practice appears here.

Information as Property

Rule 41(a)(2)(A) defines property to include documents, books, papers, any other tangible objects, and information.¹ The last word in that list carries the weight for digital evidence. The rule's categories of things a warrant may be sought for are all phrased in terms of property, so a definition that reaches information means that data can be evidence, contraband, or an instrumentality in the same way a ledger can. Probable cause, particular description, and execution then apply to a file on a server exactly as they apply to a file in a cabinet, and no parallel set of rules is needed. Without the definition, a rule written around papers and objects would leave open whether data could be seized under a warrant at all.

The constitutional requirement that a neutral magistrate decide in advance also survives the move from physical to electronic settings. In Katz v. United States the government asked the Court to exempt surveillance of a telephone booth from the usual requirement of advance authorization by a magistrate on probable cause, and the Court refused.² Skipping advance authorization replaces an objective finding made beforehand with a justification offered after the event, and that after-the-fact account is likely to be colored by hindsight. The Court added that these considerations do not disappear when the search moves from a home, office, or hotel room to a new setting, which is why the digital settings below are tested by the same warrant requirements.³

Cell-Site Records

Historical cell-site location records are held by the phone carrier, which raises the question whether the customer keeps any privacy interest in them. In Carpenter v. United States the Court held that individuals have a reasonable expectation of privacy in their historical cell-site location information even though a third-party service provider holds the records, and that the government generally must obtain a warrant supported by probable cause to access this pervasive, long-term location data.⁵ The reasoning has two links. A long record of where a phone has been reveals a person's movements over time and, through them, much of that person's private life. And the fact that the carrier keeps the file does not erase that interest, because otherwise the protection would vanish for any record that technology happens to require a company to store.

The holding yields a clean pair of outcomes. When the government wants weeks of historical cell-site records for a suspect from the carrier, it generally needs a warrant, and the magistrate must find the probable cause taught earlier.⁶ When the government instead seeks the same records with a court order that does not rest on probable cause, the order is not enough, because these records generally require a probable-cause warrant.⁷ A second decision with the same caption, Carpenter v. United States, 484 U.S. 19 (1987), involved the mail and wire fraud statutes and has no bearing on this Fourth Amendment point.⁸

Stored Data on Devices

Computers are treated as closed containers, so even when a computer is seized without a warrant, a warrant usually is required to examine the data stored on it.¹⁰ Seizing the device and reading it are two separate intrusions. The first takes the object, and the second exposes everything stored inside it, which may include a person's financial, personal, and business records. For that reason authority to seize a device does not carry authority to examine its contents. Officers who take a computer without a warrant and then want to look through the files must first obtain a warrant for the data.¹¹

The particular-description requirement is harder to satisfy for data than for physical objects. The ideal warrant would name the files sought, but police rarely know file names in advance, so they may ask instead to search for any and all files relating to financial misconduct. Because such data could be stored anywhere on the computer in any type of file, a warrant with that description would permit a search of the entire contents, which resembles the general warrants the Fourth Amendment was written to prevent.¹² The description therefore has to be tied to the records connected with the crime under investigation, and the affidavit has to support probable cause as to those kinds of records.¹³

Tracking and Remote Access

Rule 41 also contains provisions written for technology that does not stay in one place. Under Rule 41(b)(4), a magistrate judge with authority in the district may issue a warrant to install a tracking device within the district, and the warrant may authorize use of the device to track a person or property located within the district, outside it, or both.¹⁵ The reason is practical: a tracked car or package moves, so an authority that ended at the district line would stop working the moment the target crossed it. The authority attaches to installation inside the district, and the tracking may then follow the target out. A device also does its work over a period of time rather than in a single entry, and Rule 41(e)(2)(A) accordingly sets tracking-device warrants apart from the ordinary command to execute within a specified time of no more than 14 days.¹⁶

Rule 41(b)(6) addresses data that officers reach through a network. A magistrate judge with authority in any district where activities related to a crime may have occurred may issue a warrant to use remote access to search electronic storage media and to seize or copy electronically stored information located within or outside that district, if the rule's further conditions are met.¹⁷ The ordinary baseline ties a magistrate's authority to the district where the property sits, but data reached remotely may sit anywhere, so this provision keys authority to where the crime's activities occurred. On an exam stem, the conditions that follow the colon in the rule decide whether the authority is available, and they should be checked before the provision is applied.