Get a Warrant: The Government's Unconstitutional Practice of Subpoenaing Private Text Messages Directly from Personal Cell Phones

New York Law Journal
By Michael P. Robotti and Lauren Engelmeyer
February 9, 2024

Reprinted with permission from the February 9, 2024, issue of the New York Law Journal.

By Michael P. Robotti and Lauren Engelmyer

With the rise in government subpoenas directly to individuals demanding that they turn over their private text messages on their personal cell phones, lawyers should be on the lookout for potential Fourth Amendment violations. The U.S. Department of Justice (DOJ) and U.S. Securities and Exchange Commission (SEC) practice of subpoenaing private text messages directly from individuals has become so commonplace that individuals often turn over their text messages as readily as they would any other document requested. In many circumstances, though, the government needs to get a warrant to obtain text messages stored on a personal cell phone. A subpoena is not sufficient.

This article examines Supreme Court precedent requiring a warrant to search a cell phone, and what lawyers should consider when counseling clients on whether they should turn over text messages in response to a government subpoena.

Note: This article does not consider government subpoenas served on companies, which in turn require their employees to provide information on their cell phones to the companies as a condition of their employment. That scenario involves separate considerations not discussed herein. See, e.g., United States v. Ferguson, No. 3:06CR137 (CFD), 2007 U.S. Dist. LEXIS 87842, at *15-16 (D. Conn. Nov. 30, 2007).

Subpoenas Versus Search Warrants

Subpoenas are a powerful government tool because they do not require a showing of probable cause. The DOJ has broad authority to issue subpoenas for relevant information in connection with a grand jury investigation, and it can issue them for no reason other than "official curiosity." United States v. Morton Salt Co., 338 U.S. 632, 652 (1950). The SEC likewise has broad authority to issue subpoenas for relevant information in connection with an authorized administrative investigation. See United States v. Powell, 379 U.S. 48, 57-58 (1964); NLRB v. American Medical Response, 438 F.3d 188, 193 (2d Cir. 2006). This broad subpoena power accords with the "ancient proposition of law" that "the public has a right to every man's evidence." United States v. Nixon, 418 U.S. 683, 709 (1974).

The recipient of a DOJ or an SEC subpoena typically has limited means to challenge the subpoena. The recipient may challenge the subpoena as overbroad, unduly burdensome or that it seeks irrelevant information. RNR Enterprises, 122 F.3d 93, 97 (2d Cir. 1997); SEC v. Brigadoon Scotch Distributing, 480 F.2d 1047, 1056 (2d Cir. 1973). Such objections are often negotiated and resolved informally between the government and counsel for the recipient. Subpoenas are also subject to constitutional constraints. For instance, a court may quash a subpoena where a recipient invokes the Fifth Amendment act-of-production privilege. See e.g., United States v. Hubbell, 530 U.S. 27, 31-32 (2000); In re Grand Jury Subpoena Duces Tecum Dated Oct. 29,1992, 1 F.3d 87, 93 (2d Cir. 1993); SEC v. Forster, 147 F. Supp. 3d 223, 227 (S.D.N.Y. 2015).

Though less frequently invoked to challenge a subpoena, the Fourth Amendment warrant requirement also presents a constitutional limitation to subpoena enforcement. If the Constitution requires a search warrant to obtain certain information, the government cannot use a subpoena to get that information instead. See Carpenter v. United States, 138 S. Ct. 2206, 2221-23 (2018). While a federal prosecutor or an SEC attorney can easily issue a subpoena pursuant to an ongoing investigation—they simply need to fill out the PDF forms and serve it on the recipient—a search warrant involves far more procedural and constitutional hurdles.

A search warrant requires the government to prepare a detailed search warrant application, including an affidavit from a law enforcement agent, to convince a magistrate judge that there is "probable cause to believe that the legitimate object of a search is located in a particular place." Steagald v. United States, 451 U.S. 204, 213 (1981); see Fed. R. Crim.P.41. Further, the warrant must be narrowly tailored and describe with particularity the objects that will be searched and seized under the Fourth Amendment. See Mary/and v. Garrison, 480 U.S. 79, 84 (1987). "The purpose behind the warrant requirement is to insure that the judgment of a neutral...magistrate is imposed against the unbridled discretion of an official caught up in the heat of an investigation." United States v. Hermiz, 42 F. Supp. 3d 856, 866 (E.D. Mich. 2014) (quoting United States V. Blue Diamond Coal, 667 F.2d 510, 518 (6th Cir. 1981)); see United States v. Amerson, 483 F.3d 73, 82 (2d Cir. 2007) ("[A] significant reason for warrants [is] to provide a check on the arbitrary use of government power").

Given the substantive and procedural gauntlet the government must run to obtain a warrant, where it can avoid those hurdles and instead obtain information from a cell phone by subpoena, it will do so. Indeed, especially at the early stages of an investigation, the government may not be able to establish probable cause and meet the other requirements of a search warrant for a phone.

Moreover, the government may face a practical limitation on its ability to obtain information via a search warrant from a phone: in many cases, the government cannot access a password-protected phone, if the defendant refuses to provide the password. See, e.g., United States v. Rogozin, No. 09-CR-379(S)(M), 2010 U.S. Dist. LEXIS 121162, at *15 (W.D.N.Y. Nov. 16, 2010); United States v. Krischner, 823 F. Supp. 2d 665, 669 (E.D. Mich. 2010).

Where the government lacks probable cause or suspects it will not be able to access a password-protected phone through a search warrant, its only option may be to seek information from the phone via subpoena. These realities likely explain why, in recent years, the government has begun regularly using subpoenas to seek private text messages from personal phones, rather than enduring the more rigorous process required to obtain a warrant.

In some cases, there may be good reasons that a subpoena recipient does not wish to challenge a government subpoena for private text messages, such as to maintain a cooperative posture with the government or to limit the information that may need to be turned over from a phone to the text messages called for in the subpoena. Thus, the recipient and his or her counsel will not raise a Fourth Amendment objection.

But that does not mean that the Fourth Amendment does not apply and limit the government's subpoena power. It simply means that a particular recipient of a particular subpoena has chosen not to assert his or her Fourth Amendment rights. The government, though, should not take such acquiescence as license to end-run the Fourth Amendment. But based on current government practice, it appears to be doing just that.

Recent Supreme Court precedent, however, makes it clear that the Fourth Amendment fully protects text messaging—which has become one of the predominant forms of communication in our society and often contains a person's most private correspondence with friends, family, and co-workers. If the government wants to read those messages, a subpoena is not sufficient; it must get a warrant.

Supreme Court Precedent: A Reasonable Expectation of Privacy in Text Messages Requires a Warrant

The Supreme Court has long held that a "Fourth Amendment search occurs when the government violates a subjective expectation of privacy that society recognizes as reasonable." Kyllo v. United States, 533 U.S. 27, 33 (2001). Decades ago, the Supreme Court established that a government invasion of private communications is a search that requires a warrant. Katz v. United States, 389 U.S. 347, 351 (1967). The court in Katz reaffirmed that the Fourth Amendment protects "people, not places," and it held that people have a reasonable expectation of privacy in their private telephone conversations. See 389 U.S. at 351.

Since then, as communication methods and preferences have evolved with technology, the federal courts have steadily expanded fundamental Fourth Amendment protections to other types of private correspondence. See Kyllo, 533 U.S. at 34 (evolving technology must not be permitted to "erode the privacy guaranteed by the Fourth Amendment"). For example, in United States v. Jacobsen, the Supreme Court held that "[I]etters and other sealed packages are in the general class of effects in which the public at large has a legitimate expectation of privacy; warrantless searches of such effects are presumptively unreasonable." 466 U.S. 109, 114 (1984).

More recently, the U.S. Court of Appeals for the Sixth Circuit in United States v. Warshak extended the Fourth Amendment's warrant requirement to email. 631 F.3d 266, 288 (6th Cir. 2010) ("Given the fundamental similarities between email and traditional forms of communication, it would defy common sense to afford email lesser Fourth Amendment protection."). Private communication done by text message—rather than by phone call, letter, or email—is not any less protected.

Indeed, that is the logical and straightforward extension of two relatively recent Supreme Court cases:Riley v. California and Carpenter v.United States. In Riley, the court addressed the constitutionality of a warrantless search of a cell phone incident to arrest. 573 U.S. 373, 402 (2014). It held that, absent an applicable exception, a warrant is required to search a cell phone because an individual has a reasonable expectation of privacy in its contents. As the Supreme Court wrote, "[a] cell phone" is "an important feature of human anatomy" and "[t]he sum of an individual's private life can be reconstructed" through a search of a person's phone.

The court further held:

Modern cell phones are not just another technological convenience. With all they contain and all they may reveal, they hold for many Americans 'the privacies of life[.]' The fact that technology now allows an individual to carry such information in his hand does not make the information any less worthy of the protection for which the Founders fought. Our answer to the question of what police must do before searching a cell phone seized incident to an arrest is accordingly simple—get a warrant.

573 U.S. at 403 (citation omitted). In explaining the scope of its holding, the court stated: "Our holding, of course, is not that the information on a cell phone is immune from search; it is instead that a warrant is generally required before such a search, even when a cell phone is seized incident to arrest." See Carpenter, 138 S. Ct. at 2214 ("Likewise in Riley, the court recognized the 'immense storage capacity' of modern cell phones in holding that police officers must generally obtain a warrant before searching the contents of a phone").

Four years later, in Carpenter, the Supreme Court squarely rejected an argument that the government has the power to subpoena data in which an individual has a reasonable expectation of privacy under the Fourth Amendment. 138 S. Ct. at 2214. There, the government obtained an order under the Stored Communications Act for cell site location information from wireless carriers to track a defendant's location. Carpenter, 138 S. Ct. at 2212. Noting that such an order was akin to a subpoena, the court held that it was a violation of the defendant's Fourth Amendment rights, because the defendant had a reasonable expectation of privacy in his cumulative location data.

As relevant here, in response to an argument from Justice Samuel Alito (Alito, J., dissenting), the majority concluded that this type of data cannot be subpoenaed under existing Supreme Court precedent. It stated: "[T]his court has never held that the Government may subpoena third parties for records in which the suspect has a reasonable expectation of privacy." 138 S. Ct. at 2221 (citation omitted). The court further noted that, "[i]f the choice to proceed by subpoena provided a categorical limitation on Fourth Amendment protection, no type of record would ever be protected by the warrant requirement."

The court dismissed the contention that "private letters, digital contents of a cell phone—any personal information reduced to document form, in fact—may be collected by subpoena for no reason other than 'official curiosity,'" and it stated that the "subpoena doctrine" should not be used to "overcom[e] any reasonable expectation of privacy."

Taken together, Riley and Carpenter stand for the proposition that the government is required to obtain a warrant to search a cell phone because an individual has a reasonable expectation of privacy in the contents thereof and the government may not use a subpoena to circumvent that warrant requirement. Accordingly, applying Riley and Carpenter to private text messages located on a personal cell phone, the government is required to obtain a warrant to read them. It cannot compel an individual to turn over private text messages by issuing a subpoena.

Given that evolving technology has led to a significant shift in private correspondence from the telephone and letter to email and text message, this extension of basic Fourth Amendment guarantees to these new technologies should not be controversial. Just as the words one speaks into a phone are private, Katz, 389 U.S. at 352, so too are the words one types into a phone.

Considerations When Responding to a Subpoena Seeking Private Text Messages from a Personal Phone

Despite the precedent cited above, the government has become accustomed to obtaining key evidence in its investigations through subpoenas for private texts on personal phones. Counsel for the recipient of a subpoena for such messages should not be surprised if the government demands compliance over their Fourth Amendment objections. So, who wins when the government pushes for a subpoena response over such objections from a recipient?

There is little precedent testing the limits of Riley and Carpenter in the subpoena context because the issue is rarely litigated, and the recipient often negotiates a resolution with the government short of having to file a motion to quash or the government filing a motion to compel. While every case is unique, counsel advising clients responding to a subpoena should consider the strong basis under the Fourth Amendment to refuse to produce text messages in response to a subpoena, and how the government might react.

Depending on the specific circumstances, the arguments discussed above may be appropriate to raise in negotiations with the government or during motions practice. In response, the government may seek to raise a variety of arguments defending its practice of subpoenaing private text messages from personal cell phones. But these arguments are unlikely to persuade a court. We address some potential arguments below.

The Third-Party Doctrine

The government might seek refuge in the third-party doctrine, arguing that an individual relinquishes his right to privacy by voluntarily communicating with a third party. This argument, though, contradicts an unbroken line of federal court cases protecting private correspondence under the Fourth Amendment. The Fourth Amendment protects a telephone conversation with a third party (Katz), as well as letters (Jacobsen) and emails (Warshak) sent to third parties, so there is no reason text messages to third parties would be any different. See Kyllo, 533 U.S. at 34.

The court in Carpenter rejected the government's attempt to "mechanically apply []" the third-party doctrine to cell site data, concluding that such data was "qualitatively different" than "telephone numbers and bank records," to which the third-party doctrine applies. 138 S. Ct. at 2219. It explained that the third-party doctrine originally applied to records that were "not confidential communications but negotiable instruments to be used in commercial transactions," and it emphasized that "the fact that the information is held by a third party does not by itself overcome the user's claim to Fourth Amendment protection" (emphasis added).

The third-party doctrine is a particularly poor fit for text messages, because many text messaging applications are end-to-end encrypted. For example, in their privacy policies, Apple explains that only the sender and receiver(s) can access content of encrypted iMessage conversations, and WhatsApp states that "end-to-end encryption ensures only you and the person you're communicating with can read or listen to what is sent, and nobody in between, not even WhatsApp" (Apple; "About End-to-End Encryption", WhatsApp). That means that, unlike bank records and telephone numbers, end-to-end encrypted text messages are not shared with third-party service providers; such messages are only shared with the intended recipient(s).

In that regard, there is an even stronger expectation of privacy in such text messages than the phone calls at issue in Katz, where the telephone company had the ability to access the calls routed through the company. See Warshak, 631 F.3d at 42 (citing Katz). Similarly, there is a stronger expectation of privacy in such text messages than in the emails at issue in Warshak, where the court rejected the third-party doctrine despite the service provider's ability to access the emails sent through its servers. 631 F.3d at 42-43.

`SEC v. Covington & Burling'

The government might seek to rely on SEC v. Covington & Burling, No. 23-MC-00002 (APM), 2023 U.S. Dist. LEXIS 127205 (D.D.C. July 24, 2023), seemingly the only reported case that addresses the adequacy of a subpoena under Carpenter's Fourth Amendment analysis. In that case, Covington & Burling LLP (Covington) refused to produce a list of the law firm's clients in response to an SEC subpoena, relying on Carpenter to argue that the clients had a reasonable expectation of privacy in their attorney-client relationships and thus the government needed a warrant to obtain the list. 2023 U.S. Dist. LEXIS 127205, at *16.

The district court rejected Covington's argument, highlighting the "diminished expectation of privacy in the mere fact of [the clients'] attorney-client relationship," which is "often in the public domain." 2023 U.S. Dist. LEXIS 127205, at *21.

For this reason, Covington is inapplicable to a subpoena seeking private text messages stored on a personal cell phone. Unlike in Covington, the Supreme Court has already established that an individual has a reasonable expectation of privacy in the contents of his or her personal cell phone. Riley, 573 U.S. at 402. Thus, in most cases, there is no "diminished expectation of privacy" in private text messages on a personal cell phone, especially in end-to-end encrypted text messages stored on a password-protected device.

Moreover, Covington further emphasized the diminished expectation of privacy at issue in that case, by highlighting that the law firm was seeking to shield the identity of public companies, which have much less of an expectation of privacy than individuals. As the court stated, corporations "can claim no equality with individuals in the enjoyment of a right to privacy." 2023 U.S. Dist. LEXIS 127205, at *20.

Further, the court specifically noted that identifying the client names at issue "would not divulge any protected communications," in effect distinguishing that case from a case involving private correspondence on a personal cell phone. Accordingly, any attempt by the government to rely on Covington in this situation is misplaced.

Subpoena Is Not a Search

The government also might respond to a Fourth Amendment objection by arguing that it is only requesting production of text messages via subpoena and not taking possession of the individual's phone; therefore, it is not conducting a search of the phone. But "a Fourth Amendment search occurs when the government violates a subjective expectation of privacy that society recognizes as reasonable." Kyllo, 533 U.S. at 33.

Whether the government takes possession of the cell phone is irrelevant under the Fourth Amendment analysis. If a subpoena invades a reasonable expectation of privacy, such as by compelling an individual to turn over his or her private text messages, the government has conducted a search.

The Carpenter court rejected the argument that a subpoena did "not involve the direct taking of evidence," and hence did not implicate the Fourth Amendment's warrant requirement. 138 S. Ct. at 2221. The court declined to adopt the view that subpoenas are "subject[] to lenient scrutiny without regard to the suspect's expectation of privacy."

It specifically distinguished cases in which the Court had previously concluded that certain subpoenas for certain documents were not searches that required a warrant, because those cases involved "requests for evidence implicating diminished privacy interests or for a corporation's own books" (distinguishing Oklahoma Press Publishing v. Walling, 327 U.S. 186, 189 204-08 (1946), and others cases). Those cases have no bearing on private text messages in which an individual has a reasonable expectation of privacy.


Because text messaging has become one of the primary ways that we communicate privately with family, friends, and co-workers, the government will continue to attempt to mine those messages for valuable evidence in its cases. In an appropriate case, the government may be able to obtain private text messages on a personal cell phone in connection with its investigation. But the lesson from the Supreme Court is clear: the government must get a warrant to do so.

Now more than ever it is important to consider the benefits of asserting a Fourth Amendment objection in response to a subpoena for private text messages. Given this legal precedent, attorneys should be cautious about reflexively agreeing to turn over a client's private text messages from a personal phone.

Michael P. Robotti is a partner in the New York office of Ballard Spahr, where he serves as co-leader of the firm's Anti-Money Laundering team and advises financial institutions and businesses on compliance requirements. Lauren Engelmyer is an associate in the firm's litigation department, where she focuses her practice on complex business litigation and arbitration.

Subscribe to Ballard Spahr Mailing Lists

Get the latest significant legal alerts, news, webinars, and insights that affect your industry.