This paper examines the laws that regulate government use of pen registers (devices that record dialed phone numbers) and "packet sniffers" (the Internet counterpart to the pen register, roughly speaking). Following a review of the basic history and development of the statutory and constitutional law governing privacy in communications, the paper takes a closer look at Title III's use of the concept of "contents" as the touchstone of its privacy scheme, and analyzes the difficulties inherent in that scheme. The paper then considers the state of communications privacy law in light of the Fourth Amendment question, arguing that the seminal Smith decision is constitutionally suspect. A set of proposals are ultimately set forth: sharper statutory language, modest increases in substantive statutory privacy rights, and recognition of constitutional privacy protection in "non-content."