The Internet of Things and the Fourth Amendment of Effects

76 Pages Posted: 15 Mar 2015 Last revised: 8 Aug 2017

See all articles by Andrew Guthrie Ferguson

Andrew Guthrie Ferguson

American University Washington College of Law

Date Written: August 3, 2015


By 2020 there will be billions of “things” connected through the “Internet of Things.” These smart devices built within our homes, cars, smartphones, clothing, and accessories present new possibilities for technological surveillance for law enforcement. This network of smart devices also poses a new challenge for a Fourth Amendment built around “effects.” The constitutional language protecting “persons, houses, papers, and effects” from unreasonable searches and seizures must confront this change. This article addresses how a Fourth Amendment built on old-fashioned “effects” can address a new world when things are no longer just inactive, static objects, but objects that create and communicate data with other things. The article seeks to answer two questions. First, what is the definition of an “effect” for Fourth Amendment purposes in a world defined by an interconnected, network-like Internet of Things? Second, assuming that a Fourth Amendment “effect” has a broader definition that potentially includes the digital information embedded in the object and the wireless communication signals emanating from the device, then what expectation of security should attach to these effects? As to the first question, this article argues that the Fourth Amendment’s definition of effects can encompass the smart objects and related data that populate the Internet of Things. As a doctrinal matter, the Fourth Amendment has evolved beyond narrow constitutional definitions. “Persons” now include more than physical bodies, including clothing, bodily fluids, and even corporations. “Papers” now include digital recordings, writings, business documents, and other communication. “Houses” now include curtilage, barns, apartments, and commercial spaces. So too with “effects” – a broader understanding can be created consistent with Fourth Amendment principles. This definition would include a defined portion of the effect’s functionality including its necessary communication with other devices and stored data. An “effect” is no longer just the physical object but also the smart data and communicating signals emanating from the device.

As to the second question, once effects are defined as including not just the physical object, but also the data and functionality of the object, the threshold question of whether there was a Fourth Amendment search becomes quite complicated. Is the virtual recovery of stored data in a device a search? Is the interception of wireless data from interconnected sensors a search? Drawing a line to demarcate a threshold of protection in a non-physical world presents real challenges to technology and Fourth Amendment doctrine. The project motivating this article is redefining an effect to answer these difficult questions.

How the Fourth Amendment adapts to these new sensor surveillance systems will be a central issue in the coming years. This article seeks to establish a framework for analyzing the Internet of Things within the current Fourth Amendment doctrine, as well as to show the existing gaps in coverage. The article then seeks to provide an alternative theoretical framework to fill these doctrinal gaps.

Keywords: Fourth Amendment, internet of things, IoT, effects, search, seizure, smart devices, sensor, surveillance

Suggested Citation

Ferguson, Andrew Guthrie, The Internet of Things and the Fourth Amendment of Effects (August 3, 2015). 104 Calif. L. Rev. 805 (2016) , Available at SSRN:

Andrew Guthrie Ferguson (Contact Author)

American University Washington College of Law ( email )

4300 Nebraska Avenue, NW
Washington, DC 20016
United States

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