Perhaps the most interesting brief is this one filed by "tech companies." Although they don't take a position on this specific case, which argues that the third party doctrine is no longer workable in this modern era
The Internet and Internet-connected devices have revolutionized nearly every facet of our lives. Ameri-cans rely daily on services made possible by networked technologies—from email, smartphones, and web-based social media the Court has already encountered to new and evolving products and applications in the “Internet of Things,” such as smart-home devices that can be used to control room temperature and lighting, order groceries, and perform a multitude of other tasks. These devices and services not only confer immense value on users and society, but in many instances are considered practical necessities of modern life.
Using these technologies often involves transmit-ting highly personal information through the networks and applications of digital service providers. That in-cludes transmission of metadata—
i.e., data about da-ta—generated by automated processes that are part of the background operation of digital devices and applica-tions. Such transmissions are inherent features of how the Internet and networked devices work. Short of forgoing all use of digital technologies, they are una-voidable. And this transmission of data will only grow as digital technologies continue to develop and become more integrated into our lives. Because the data that is transmitted can reveal a wealth of detail about people’s personal lives, however, users of digital technologies reasonably expect to retain significant privacy in that data, notwithstanding that technology companies may use or share the data in various ways to provide and improve their services for their customers. Fourth Amendment doctrine must adapt to this new reality. Although amici do not take a position on the outcome of this case, they believe the Court should refine the application of certain Fourth Amendment doctrines to ensure that the law realistically engages with Internet-based technologies and with people’s ex-pectations of privacy in their digital data. Doing so would reflect this Court’s consistent recognition that Fourth Amendment protections, governed as they are by reasonable expectations of privacy, must respond to changes in technology that implicate privacy. Indeed, in declining to extend the search-incident-to-arrest ex-ception to searches of cell phones in Riley v. California, 134 S. Ct. 2473 (2014), this Court has already signaled that digital information deserves special consideration, largely because Internet-connected devices such as smartphones “are not just another technological con-venience,” but are necessary to participate in the mod-ern world, and “hold for many Americans ‘the privacies of life.’”
In the digital context, inflexible doctrines that cat-egorically foreclose any protection for data automatical-ly generated by ordinary digital activity—or that will be generated by the yet-to-be-conceived technologies of tomorrow—are not sustainable. In particular, the analog-era notion that transmission of data to a third party is necessarily “voluntary” conduct that precludes Fourth Amendment protection should not apply in a world where devices and applications constantly transmit data to third parties by dint of their mere op-eration. No constitutional doctrine should presume that consumers assume the risk of warrantless government surveillance simply by using technologies that are beneficial and increasingly integrated into modern life. Similarly, the fact that certain digitally transmitted information might have been traditionally classified as “non-content” should not unconditionally bar Fourth Amendment protection, as this data can of-ten be highly revealing of the intimate details of a us-er’s life. Rather than adhere to rigid Fourth Amendment “on/off” switches developed in the analog context, courts should take a more flexible approach that realis-tically reflects the privacy people expect in today’s dig-ital environment. Consistent with the general reasona-ble-expectation-of-privacy inquiry, courts should focus on the sensitivity of the data at issue and the circumstances of its transmission to third parties. That approach would better reflect the realities of today’s digital technologies and accommodate the technologies of the future.
*Full disclosure -- I am counsel for NACDL in this brief.