These cases are United States v. Dunn, 107 S.Ct. 1134 (1987), and Texas v. Brown, 460 U.S. 730 (1983), (artificial illumination); United States v. Knotts, 460 U.S. 276 (1983), United States v. Karo, 468 U.S. 705 (1984), (electronic tracking devices); California v. Ciraolo, 476 U.S. 207 (1986), and Florida v. Riley, 57 U.S.L.W. 426 (U.S. Jan. 23, 1989), (aerial surveillance); and Dow Chemical Co. v. United States, 476 U.S. 227 (1986), (image-magnifying aerial photography). In addressing the issue of when visual surveillance constitutes a 'search' subject to Fourth Amendment restrictions and standards, the Court has considered three separate factors: the sophistication (or sense-enhancing capacity) of the surveillance equipment; its availability to the general public; and the nature of the information sought and revealed by the surveillance. The court's approach to technology is that the more sophisticated the equipment, the more its use is likely to intrude. If the equipment is readily available to the general public, it often may be unreasonable for a person to expect constitutional protection from its use. The third factor in the court decisions - the nature of the information sought and obtained by the surveillance - may provide precisely the limiting principle needed in these cases. At present few guidelines exist as to what kind of information is protected from unauthorized technologically enhanced visual surveillance, and what information is not. Moreover, confusion is inevitable as to the comparative significance of the three factors - sophistication (sense-enhancement) and availability of the equipment, and informational privacy expectations - in any given case. Surveillance technology presents complex questions of law, fact and values. 239 footnotes.