Fourth Amendment seizures of computer data.

• Author: Kerr, Orin S.

ARTICLE CONTENTS INTRODUCTION I. THE SEIZURE PUZZLE A. Introduction to the Seizure Puzzle B. Precedents on Copying as a Seizure II. SOLVING THE SEIZURE PUZZLE A. The Power To Seize as the Power To Freeze B. Copying as Freezing III. THE LIMITATION OF COPYING WITHOUT HUMAN OBSERVATION A. Copying as Freezing Versus Copying as an Aid to Memory B. Copying as an Aid to Memory in Hicks and Aseltine, and the Close Case of Jefferson C. Alternative Ways of Distinguishing Hicks and Aseltine IV. THE LIMITATION OF INTERRUPTING THE COURSE OF POSSESSION A. Seizures and the Stream of Transmission B. Precedents from Postal Letters and Packages C. Applying Course-of-Transmission Principles to Computers CONCLUSION INTRODUCTION

Imagine the police take away a suspect's computer, make a digital copy of its contents, and then give the computer back to the suspect. The police do not open the copy, but they keep it in their custody in case they need to access it later. Does the combined act of copying the files and retaining the copy trigger the Fourth Amendment?

Next imagine that FBI agents believe a particular person is using the Internet to commit a crime. Agents install a surveillance tool at the target's Internet service provider (ISP), and the tool generates copies of all of the target's incoming and outgoing email. The email is copied to a file, but no human being actually looks at the file. Instead, the agents keep the file in case they develop probable cause to look through it for evidence. Again, does the Fourth Amendment allow it?

The answer to both scenarios depends on whether copying computer files without looking at them constitutes a Fourth Amendment "seizure." (1) If copying a computer file amounts to a seizure, then the government cannot make and retain a copy absent special circumstances. On the other hand, if copying is not a seizure, then the government can make and retain the copy without restriction. The Fourth Amendment will limit looking through the copy because that is a Fourth Amendment "search." (2) But what if the government wants to make a copy and hold it? Does that constitute a "seizure"?

The answer is tremendously important, as it determines the legal framework that governs almost every digital evidence investigation. Computer search and seizure inverts the usual pattern of criminal investigations. When searching for traditional physical evidence, the police first search for property and then seize it. Computer technologies often require investigators to obtain a copy first and then search it later. (3) Nearly every case begins with copying data that will later be searched, and government investigators often will prefer to copy more rather than less if the Fourth Amendment allows it.

The question is also doctrinally uncertain. The Supreme Court has said that a seizure of property occurs when government action meaningfully interferes with an individual's possessory interests in that property. (4) This could be interpreted in two different ways. On one hand, perhaps copying does not interfere with a possessory interest because that interest is limited to hardware and the copy of the data it stores. On the other hand, perhaps copying interferes with a possessory interest because a possessory interest extends to both the original and any copies made from it. The test itself does not suggest an answer. To make matters more complicated, precedents from earlier technologies such as physical copying, photographic copying, and wiretapping are decidedly mixed. (5) The Supreme Court's decisions that touch on the question are rather hard to decipher. The Court held in one case that copying a number does not seize anything, while it strongly suggested in another case that copying data does seize it. (6) Whether and when copying amounts to a seizure remains an unsolved puzzle.

This Article attempts to solve the puzzle by offering a test for when copying data constitutes a Fourth Amendment seizure. It argues that copying data "seizes" it under the Fourth Amendment when copying occurs without human observation and interrupts the course of the data's possession or transmission. It arrives at this definition by reaching back to the general purposes of regulating seizures in Fourth Amendment law and then applying those functions to the new environment of computers. The test it offers prevents the government from copying data without regulation, and yet also answers the objections that have puzzled scholars and made it difficult to apply the old definition of seizures in the new environment.

Under my approach, copying is neither never nor always a seizure. Whether copying amounts to a seizure depends both on whether it is pre-observation or post-observation and on whether it interrupts the intended transmission or use of the data. Past technologies have not raised the need for these distinctions, as copying has always been post-observation: a person has needed to see data in order to copy it. Computers permit machine copying without human observation, which requires a more nuanced understanding of when copying constitutes a seizure. The new approach reconciles the case law from prior technologies and then suggests a workable definition that sensibly translates the traditional physical concept of Fourth Amendment seizures to a digital environment. (7)

Finally, this Article acknowledges a change in my own thinking. A few years ago, I argued that mere copying should not be considered a Fourth Amendment seizure. (8) I acknowledged that copying ordinarily will be regulated by the Fourth Amendment. To my mind, however, copying was at most regulated by the restrictions on searches rather than seizures, and those restrictions were limited to copying that interfered with the operation of the machine from which the copy was made. I have now concluded that my prior approach was wrong. My earlier approach did not recognize the importance of access to data in the regulation of government evidence collection. Further, my earlier approach did not appreciate that a middle ground was possible to avoid some of the overbroad results that seem to follow from labeling copying a seizure. This Article identifies the new middle ground and explains why I now reject my earlier view.

The Article contains four Parts. Part I introduces the difficult question of whether copying data seizes it. Part II presents the basic argument for why copying should be considered a seizure. Parts III and IV introduce two key limitations. Part III limits seizures to copying without human observation, and Part IV limits seizures to copying outside the course of delivery or possession.

1. THE SEIZURE PUZZLE

   Criminal investigators often obtain copies of computer files without first looking through them. Because computers can store a remarkable amount of information, sifting through the data can be very time-consuming. Faced with this reality, investigators often prefer to copy first and search later. (9) The digital copies remain on a government computer awaiting viewing and analysis. Whether that copying and storage amounts to a Fourth Amendment seizure remains unclear. This Part explains why the answer is unclear, setting up the puzzle that the rest of the Article will attempt to solve.

   1. Introduction to the Seizure Puzzle

      The Fourth Amendment rules for collecting physical evidence are well established. The Fourth Amendment prohibits unreasonable searches and seizures. (10) When the government invades a private space, violating a reasonable expectation of privacy, that invasion constitutes a search. (11) When the government then spots evidence or contraband and takes it away for use at trial, that physical taking of the evidence amounts to a seizure. (12) As the Supreme Court has explained, a seizure of property occurs when the government meaningfully interferes with a person's possessory interest in property. (13) The definition of a seizure is easy to apply to physical property. Physical property is possessed when a person has knowledge and control over it. (14) As a result, a seizure of physical property occurs when the government takes control of the property and denies control to others.

      But how should this apply to computer data? If computer hardware stores data, and the government takes the hardware away, then surely the data it contains is seized along with the hardware. (15) But what if the government copies the data onto its own storage device and leaves the original copy undisturbed? At that point courts face a difficult choice. If the possessory interest that the Fourth Amendment protects refers only to the original, then the government's creation of a copy does not interfere with the owner's possessory interest and does not amount to a seizure. On the other hand, if the possessory interest that the Fourth Amendment protects refers to the data itself--the original, or any copy made from it--then the copying does interfere with the possessory interest and is a seizure. The question is this: does the possessory interest refer to control of the original data, or does it refer to control of the data itself, including any copies?

   2. Precedents on Copying as a Seizure

      Existing precedents are divided on whether copying information constitutes a Fourth Amendment seizure. Some decisions hold or strongly suggest that copying is not a Fourth Amendment seizure, while others hold or strongly suggest that it is. The leading case for the view that copying does not constitute a seizure is Arizona v. Hicks. (16) In Hicks, a police officer searching an apartment under exigent circumstances saw an expensive stereo in an otherwise squalid apartment. He suspected that the stereo was stolen, so he lifted up the stereo, observed the serial number, and wrote the number down. The officer later used the number to confirm a match between the stereo he saw and equipment that had been reported stolen. The Supreme Court held that copying the serial number did not seize...