Introduction and Summary of the Argument:

The government invites this Court to make three critical missteps, all of which could have far-reaching and unintended consequences for the future of digital privacy rights in the United States.

First, the government urges the Court to hold that the Fourth Amendment is not implicated when the government or its agents copy or transfer a user’s emails, but only upon disclosure or review of the emails’ content. To the contrary, if Microsoft copies, transfers, or otherwise accesses email at the government’s behest, the Fourth Amendment applies and requires a warrant. This is because Microsoft is acting as a government agent and seizing the user’s private communications on the government’s behalf, even before an investigator reads them. Thus, a Fourth Amendment “search and seizure” occurs when Microsoft accesses, copies, or moves a user’s data to fulfill the government’s demand, regardless of when, where, or even whether investigators might later search it. Were this Court to suggest otherwise, the government could then try to compel companies to copy, transfer, decrypt, analyze, or give government agents log-on access to user email accounts to make private data searchable to investigators—all without obtaining a warrant or undergoing constitutional scrutiny. Prohibiting these kinds of seizures for the purpose of gathering private information is exactly why the founders adopted the Fourth Amendment in the first place.

Second, the government conflates subpoenas with search warrants, implying that the former are sufficient to search and seize emails. Pet. Br. at 36 (“With a subpoena, a court ‘may order the witness to produce any books, papers, documents, data, or other objects the subpoena designates.’” (citing Fed. R. Crim. P. 17(c)(1))). In fact, a subpoena constitutionally cannot compel disclosure of a customer’s email or other private communications under the Fourth Amendment. Emails, like text messages,  are “essential means or necessary instruments for self- expression, even self-identification,” City of Ontario v. Quon, 560 U.S. 746, 760 (2010). As a result, government access to them invades a reasonable expectation of privacy and generally requires a warrant based on probable cause. See United States v. Warshak, 631 F.3d 266, 285–86 (6th Cir. 2010) (“Given the fundamental similarities between email and traditional forms of communication, it would defy common sense to afford emails lesser Fourth Amendment protection.”). In short, subpoenas are insufficient instruments for accessing email through a service provider under the Fourth Amendment. Amici urge the Court to make clear that a mere subpoena cannot authorize law enforcement to search and seize American email from a service provider.

Third, the government’s position will increase the risk that investigative demands from other countries’ governments will interfere with the privacy and property interests of people in the United States. If this  Court holds that the U.S. government can compel disclosure of foreign data from any service provider with operations in the United States, then foreign governments are more likely to reciprocate by seeking Americans’ data through service providers with a presence abroad. As a result, U.S. communications providers such as Microsoft will have less ability to contest foreign government demands to copy and search communications belonging to U.S. persons, even though foreign legal standards may be far less protective than those applicable in this country.

Amici urge the Court to avoid these missteps, which could dramatically curtail Fourth Amendment rights for Americans’ electronic communications data.