The third party doctrine after Carpenter does not make IP addresses and subscriber information protected by the Fourth Amendment or the state constitution. State v. Mixon, 2021 Ariz. LEXIS 3 (Jan. 11, 2021):
¶1 We consider whether the Fourth Amendment to the United States Constitution or article 2, section 8 of the Arizona Constitution requires law enforcement officials to secure a judicially-authorized search warrant or order to obtain either (1) a user’s Internet Protocol (“IP”) address or (2) subscriber information the user voluntarily provides to an Internet Service Provider (“ISP”) as a condition or attribute of service. We hold that neither the federal nor the Arizona Constitution requires a search warrant or court order for such information and that law enforcement officials may obtain IP addresses and ISP subscriber information with a lawful federal administrative subpoena.
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¶18 As with bank records and dialed telephone numbers, an internet user voluntarily provides subscriber information and IP addresses to third-party ISPs and servers. Subscriber information and IP addresses also do not reveal the substance or content of the internet user’s communication any more than the information affixed to the exterior of a mailed item. See Shuntich & Vogel, supra ¶ 3, at 51 (noting that 18 U.S.C. § 2701 et seq. prohibits companies from disclosing “contents of a communication,” but they may turn over non-content information like IP addresses, phone numbers, and physical addresses in response to a subpoena); cf. Forrester, 512 F.3d at 511 (“In a line of cases dating back to the nineteenth century, the Supreme Court has held that the government cannot engage in a warrantless search of the contents of sealed mail, but can observe whatever information people put on the outside of mail, because that information is voluntarily transmitted to third parties.”).
¶19 In Carpenter, decided nearly 40 years after Smith, officers accessed cellphone data, commonly known as cell-site location information (“CSLI”), to reveal a suspect’s movements over the course of 127 days. 138 S. Ct. at 2217. CSLI is generated by a cellphone whenever it receives a text, email, call, or when an app seeks to refresh data. Id. at 2220. As a result, CSLI is generated continuously without a user’s affirmative act. The Court described CSLI evidence as “detailed, encyclopedic, and effortlessly compiled,” id. at 2216, and noted that it “tracks nearly exactly the movements of its owner,” allowing the government to achieve “near perfect surveillance, as if it had attached an ankle monitor to the phone’s user,” id. at 2218. Concerned that CSLI could be used to continuously and effortlessly surveil cell phone users, the Court created a “narrow” exception to the third-party doctrine, requiring the government to obtain a search warrant for CSLI. Id. at 2220. The Court emphasized that a “detailed chronicle of a person’s physical presence compiled every day, every moment, over several years” implicated privacy concerns far exceeding those in Smith and Miller. Id.
¶20 Following Carpenter, every federal appellate court addressing the issue has affirmed that the Fourth Amendment’s warrant requirement does not reach IP addresses and ISP subscriber information. See, e.g., United States v. Hood, 920 F.3d 87, 92 (1st Cir. 2019) (holding that IP addresses are subject to the third-party doctrine and fall outside the scope of Carpenter); United States v. Contreras, 905 F.3d 853, 857 (5th Cir. 2018) (ruling that, postCarpenter, ISP subscriber information “falls comfortably within the scope of the third-party doctrine”); see also United States v. Wellbeloved-Stone, 777 F. App’x 605, 607 (4th Cir. 2019) (declining to revisit Bynum’s holding that subscriber information was not protected by the Fourth Amendment in light of Carpenter); United States v. VanDyck, 776 F. App’x 495, 496 (9th Cir. 2019) (declining to revisit Forrester’s holding that IP addresses and ISP subscriber information are not protected by the Fourth Amendment in light of Carpenter).
¶21 Although this Court is not bound by federal appellate courts’ interpretations of federal constitutional provisions, see State v. Montano, 206 Ariz. 296, 297 ¶ 1 n.1 (2003), we may embrace them to “further predictability and stability of the law.” See Weatherford ex rel. Michael L. v. State, 206 Ariz. 529, 533 ¶ 9 (2003). Here, because the federal appellate courts’ jurisprudence is uniform and sound, we decline to depart from it.