在美國，Katz v. United States案認為，美國聯邦憲法第四修正案的保護範圍涵蓋了人民的電話通訊內容。但是，美國聯邦最高法院於Smith v. Maryland案中則判定，依據風險承擔理論及隱私的合理期待理論，人民對於其通信紀錄並不能主張憲法上的隱私權。不過，美國聯邦國會仍制定了一連串的法案，用以規範偵查機關對通信紀錄的調取行為，以更有效地保障人民的隱私權。 司法院大法官會議第六三一號解釋明白表示，關於通訊的有無、對象、時間、方式及內容等事項，均受有憲法第二十二條的保護。分析後可知，相關法規並未能符合本號解釋的意旨，使得偵查機關可以恣意調取通信紀錄，而有不當侵害人民通訊隱私之嫌。是故，本文建議，我國的相關法律應予修正，於調取較為私密的通信紀錄時，應採行法院審查的機制，以更為有效地保障人民的基本權利。 In the U.S., Katz v. United States held that the contents of telephone conversations are protected by the Fourth Amendment. However, in Smith v. Maryland, the Supreme Court, referring to the reasonable expectation of privacy rule and the assumption of risk rule, held that call detail records (CDRs) are not guaranteed by the Fourth Amendment. In order to protect people's communication privacy, Congress enacted several acts to govern the police's obtainment of CDRs. J.Y. Interpretation No. 631 stated that our constitution article 22 protects information about the existence, target, time, method and contents of communications. Nevertheless, our law and regulations do not comply with this interpretation. Therefore, law enforcement may arbitrarily obtain CDRs and improperly intrude upon people's privacy. This article suggests that our relevantlaw should be amended. In addition, in order to better protect people's communication privacy, when police request CDRs of a more private nature, court authorization should be obtained in advance.