The United States Supreme Court has determined that cellphone location data is protected under the Fourth Amendment, impacting the legality of geofence warrants used in criminal investigations.

美國最高法院判定手機位置數據受第四修正案保護，影響了刑事調查中使用地理圍欄搜查令的合法性。

The judicial determination emerged from Chatrie v. United States, a case originating from a 2019 armed robbery in Midlothian, Virginia. Law enforcement utilized a geofence warrant to compel Google to identify all mobile devices within a 17.5-acre perimeter during a specific two-hour window. This process involved a tripartite collaboration: the definition of a spatial-temporal boundary, the provision of anonymized device lists by the service provider, and the subsequent 'unmasking' of specific identities. This methodology represents a reversal of traditional investigative protocols, as it aggregates data from all individuals in a vicinity to identify a suspect, rather than targeting a specific individual based on prior probable cause.

此司法判定源於「Chatrie 訴美國案」，該案始於 2019 年發生在維吉尼亞州 Midlothian 的一起持械搶劫案。執法部門利用地理圍欄搜查令，強制 Google 識別在特定兩小時窗口內、 17.5 英畝周邊範圍內的所有行動裝置。此過程涉及三方協作：定義時空邊界、由服務供應商提供匿名裝置清單，以及隨後對特定身份的「去匿名化」。這種方法代表了傳統調查協定的反轉，因為它是透過彙整附近所有個人的數據來識別嫌疑人，而非根據先前的合理理由針對特定個人。

Institutional friction exists regarding the 'particularity' requirement of the Fourth Amendment. The government contended that users forfeit privacy expectations by opting into location services. However, the Court, in a 6-3 decision, rejected this premise, asserting that ordinary utilization of smartphone technology does not constitute a waiver of constitutional protections. This ruling aligns with the precedent established in Carpenter v. United States (2018), which recognized a reasonable expectation of privacy in cell site location information. Conversely, the dissent argued that information voluntarily surrendered to a third party lacks such privacy expectations.

關於第四修正案的「特定性」要求，制度上存在分歧。政府主張用戶透過選擇開啟位置服務，即放棄了對私隱的期望。然而，法院以 6 比 3 的裁決否決了這一前提，認定對智慧型手機技術的正常使用並不構成對憲法保障的放棄。此裁決與 2018 年「Carpenter 訴美國案」確立的先例一致，即認可對手機基地台位置資訊具有合理的私隱期望。相反，反對意見則認為，自願提交給第三方的資訊缺乏此類私隱期望。

Statistically, the adoption of this surveillance mechanism has seen exponential growth. Google reported a 1,500% increase in geofence requests between 2017 and 2018, with such warrants comprising over 25% of all law enforcement requests to the company between 2021 and 2023. The technical infrastructure enabling this capability relies on a synthesis of cell tower data, Wi-Fi connectivity, and Bluetooth signals, often processed via artificial intelligence to derive behavioral insights.

從統計數據來看，這種監控機制的採用呈指數級成長。Google 報告指出，2017 年至 2018 年間，地理圍欄請求增加了 1,500%；在 2021 年至 2023 年間，此類搜查令佔執法部門向該公司所有請求的 25% 以上。實現此功能的技術基礎依賴於手機基地台數據、Wi-Fi 連接和藍牙訊號的綜合運用，且通常透過人工智慧處理以獲取行為洞察。

The Supreme Court has remanded the case to the 4th U.S. Circuit Court of Appeals to determine if the specific geofence warrant in the Chatrie case adhered to constitutional requirements.

最高法院已將案件發回第四巡迴上訴法院，以判定 Chatrie 案中的特定地理圍欄搜查令是否符合憲法要求。