For the first hundred years of the Fourth Amendment’s life, gains in the technology of surveillance were modest. With the advent of miniaturization and ever-increasing sophistication and capability of surveillance and detection devices, the Supreme Court has struggled to adapt its understanding of “search” to the constantly evolving devices and methods that challenge contemporary understanding of privacy. In response to surveillance innovations, the Court has taken varying positions, focusing first on property-based intrusions by government, then shifting to privacy expectations, and, more recently, resurrecting the view that a trespass to property can define search.

This article surveys this constitutional odyssey, noting the inadequacies of each phase’ s approach. It then suggests a reconceptualization of search doctrine better designed to align constitutional protection with the moving target of investigative techniques. The view of privacy, central to the Fourth Amendment, is recast as a broader, and more representative, normative component rather than a simple risk-assessment. Investigative motive or intent, which only intermittently has played a part in the definition of search, is proposed as a constant factor within search analysis. And trespass doctrine, only recently back from the dead, is broadened and refocused to emphasize invasiveness more generally. With candid recognition of the weaknesses and difficulties inherent in all of these modes of analysis, the article makes the case for taking up the hard job of conforming the language, tradition, and popular expectations of constitutional protection to the realities of an ever-changing surveillance landscape.