The intent of this thesis is to examine the future of the third-party doctrine with the proliferation of technology and the online data we are surrounded with daily, specifically after the United States Supreme Court's decision in Carpenter v. United States. In order to better understand the Supreme Court's reasoning in that case, this thesis will review the history of the third-party doctrine and its roots in United States v. Miller and Smith v. Maryland. A review of Fourth Amendment history and jurisprudence is also crucial to this thesis, as it is imperative that individuals do not forfeit their Constitutional guarantees for the benefit of living in a technologically advanced society. This requires an understanding of the modern-day functional equivalents of "papers" and "effects." Furthermore, this thesis will ultimately answer the following question: Why is it legally significant that we protect at least some data that comes from technologies that our forefathers could have never imagined under the Fourth Amendment? Looking to the future, this thesis will contemplate solutions on how to move forward in this technology era. It will scrutinize the relevancy of the third-party doctrine due to the rise of technology and the enormous amount of information held about us by third parties. In the past, the Third-Party Doctrine may have been good law, but that time has passed. It is time for the Third-Party Doctrine to be abolished so the Fourth Amendment can join the 21st Century.

大法官在釋字第689號解釋中，首次在解釋文中引進美國法上的「合理隱私期待」概念，以作為人民是否受到憲法隱私權保障的判定標準。事實上，「合理隱私期待」的概念在我國法上並不令人感到陌生。例如，通訊保障及監察法第3條第2項即明確規定：「前項所稱之通訊，以有事實足認受監察人對其通訊內容有『隱私或秘密之合理期待』者為限」。 除了尾隨、全天候視覺監控等類似的古老方法，隨著科技的進步，諸如以衛星為基礎的汽車導航系統、以基地台為基礎的行動電話定位服務等低成本、高效率的定位科技，可以更輕易且嚴重地侵害我們的私生活及隱私。當定位科技成為我們每天生活的一部分時，如何在這樣的脈絡下正確地操作「合理隱私期待」概念，已成為一項重要的議題。 惟國內學術文獻對於如何正確地操作「合理隱私期待」，似乎欠缺全面性地研究。為了填補國內的空白，本文進行了美國及台灣案例法之深入比較分析，尤其是關於合理隱私期待及定位裝置的判決。本文指出了以往我國及美國法院判決的問題，以及邏輯矛盾之處。為了達到更加一致、正確的判決結果，本文認為，在操作合理隱私期望概念時，法院應著重於四個因素，其分別是：「資訊的性質」、「侵害的手段」、「侵害的場所」及「第三人原則」。 / In J.Y. Interpretation No. 689, the Constitutional Court , for the first time, employs the concept of “reasonable expectation of privacy”, originated from the United States, in order to determine whether an individual enjoys a constitutionally protected right to privacy. The concept, however, is not new to our legal system. For example, Paragraph 2, Article 3 of the Communication Protection and Surveillance Act provides: “The communications referred to in the preceding paragraph shall be limited to those for which there is an adequate showing of facts that a person subject to surveillance would have a reasonable expectation of privacy or confidentiality with respect to the content of the communications.” In addition to tailing, around the clock visual surveillance and similar old-fashioned methods, with the advance in technology, our private life and privacy could be more easily and greatly intruded by low-cost, high-efficiency location positioning technology, such as satellite-based car navigation system and cell sites-based cellphone positioning service. When location positioning technology becomes part of our everyday life, how to properly apply the concept of “reasonable expectation of privacy” in this context has also become an important issue. So far, there seems to lack a comprehensive study on the aforementioned issue in domestic academic literature. To fill the gap, this thesis conducts an in-depth comparative analysis of both U.S. and Taiwan case law, especially those involving reasonable expectation of privacy and location positioning devices. This thesis points out the problems and logical inconsistencies in past decisions in both jurisdictions. In order to reach a more consistent and appropriate result, this thesis argues that when applying the reasonable expectation of privacy test, courts should focus on four factors which are: “nature of information,” “measure of infringement,” “the place where the intrusion happens,” and “third party doctrine.”