No American with any exposure to the mass media in the 1990s can be unaware of the concept of the "information superhighway." (9) Video, audio, text, and numbers will all be stored and transported as digital data, allowing homes and businesses to connect to each other and to giant information storehouses with an ease never before imaginable. The same computer that balances your checkbook and processes your letters will work as a gateway to a new world; you will be able to call up this week's episode of Star Trek, peruse Shakespearean sonnets or Hegelian philosophy, video conference with your sister in Hawaii, or wander through L.L. Bean's electronic warehouse. And the gateway will work both ways: From your office or the airport, you will be able to connect to your home to get your video messages, update your calendar, grab a video of your dog to show your colleagues, or double-check the address of a friend in Taiwan.

Cyberspace may be described as the nonphysical "place" where electronic communications happen and digital data are located. In its most narrow formulation, "cyberspace" is a synonym for the Internet, "an immense network of networks that connects an estimated twenty million computer users by telephone lines to thousands of electronic information storehouses worldwide."(10) Every "futuristic" possibility described in the preceding paragraph is already a reality on the Internet. Not only can one access great storehouses of information from a machine in one's home or office, but one can access that machine from thousands of miles away.(11)

Of course, if it is possible for one person to access her own machine through public networks, then it is also possible for others to do so. These others may be invited guests allowed into limited areas of the owner's system to share information, or they may be unwanted intruders who have connected to her computer to search for details about her work, her system, and her life. (12) For the inquisitive, a computer's hard drive can be a treasure trove of *1096 information,(13) and if the intruder is sophisticated, the owner may never even realize that anyone unauthorized has accessed her system at all.(14)

As we enter a world in which people increasingly transact and record their lives on computers, and in which those computers increasingly are connected to public networks, the prospect of a search through one's hard drive seems more threatening. Christopher Slobogin and Joseph Schumacher conducted a survey to measure people's subjective sense of the intrusiveness of various governmental actions, and they discovered that the "tapping into [a] corporation's hard drive" seemed almost exactly as intrusive as a "search of [a] college dormitory room." (15) And while today in 1996 one might plausibly claim that anyone on the Internet has voluntarily assumed a lessened expectation of privacy by connecting, this argument becomes increasingly unreasonable the more digital connections become central to our lives. (16) At an almost unbelievable rate, private life is moving into cyberspace: The Internet is growing at a rate of approximately ten percent per month, (17) and people are using the Net not only to exchange ideas and data but to conduct courtships, financial transactions, and more. Corporate offices are going on- line at a similar rate, connecting individual office computers to the vast potential of the Internet. One has only to look at the wave of billion-dollar mergers and deals in the cable, telephone, entertainment, and banking industries to appreciate how many believe that cyberspace will soon be as ubiquitous and indispensable as televisions, telephones, and radios. (18)

Of course, the same digital lines that allow people to send videos of their children to each other also allow them to send videos of child pornography to each other. These same lines that can deliver software instantly from a manufacturer can also be used to exchange, at virtually no cost, perfect copies of pirated music, copyrighted photographs, or unauthorized commercial software. Stolen credit card numbers, telephone access codes, and programs designed specifically to break into other computers (19) inevitably find their way through the network. This is the world of digital contraband.

More precisely, digital contraband is any computer file that, outside of very specific authorized exceptions, cannot be legally possessed. For example, mere ownership of digital videos of child pornography constitutes a federal crime. (20) Similarly, owning a "cracked" copy of a commercial program -- one that has been illegally modified to remove licensing protection -- is a violation of copyright or contract law. (21) Of course, there are some legal uses of digital contraband, (22) but as with traditional contraband, the mere possession of the analogous digital files would create a strong presumption of illegal activity by the owner.

Just as possessors of digital contraband may use the Internet to transfer files back to their hard drives, law enforcement agencies might use the fact that such hard drives are connected to the Internet to seek out evidence of illegalities. The interest that a law enforcement officer might have in examining the contents of a hard drive is obvious; the trove of information there may yield important insights into crimes that the owner may have committed. (23) At the same time, the privacy interest that an individual may *1098 have in the hard drive is also obvious; regardless of whether or not the officer finds evidence of a crime, he may well learn much about the owner's private life in the process of looking through the drive. (24) A number of commentators have written recently about the need for a warrant to ensure limits to the range of the examination -- and, consequently, the potential for violation of privacy -- possible in a hard drive search. (25)

All of these commentators have assumed that a human investigator will be examining the hard drive to evaluate its contents. Nevertheless, there are certain types of investigations -- particularly those focused on digital contraband -- in which no human is needed to determine the presence or absence of relevant evidence. A computer program can be designed, for instance, to search through a hard drive and report only the presence or absence of an exact copy of a certain piece of illegally modified software. (26) Such an object- targeted search program would ignore any legitimate copy of the commercial software, as well as any copy that was cracked in even a trivially different way. (27) The program would naturally also ignore everything else on the disk, no matter how blatantly illegal -- or sensationally intriguing -- a human investigator might find that information.

Since such a search program would require an exact copy of the target digital contraband when seeking matching files, the search would be of limited use in targeting particular individuals under suspicion. Say an officer suspects an individual of trafficking in child pornography. The officer could not simply turn the search program loose with the orders that it find any sexually explicit material involving underaged participants. (28) Instead, the officer would need a copy of a particular digital video clip that he believed the suspect possessed, and the search program would tell the officer nothing more than whether that particular clip was on the system. If the suspect had a slightly different video or was clever enough to keep the video encrypted or located on a removable cartridge that was not accessible from the Internet, the search would fail.

However, let us imagine for the moment that the government had acquired technical access sufficient to run such a search program on a large number of *1099 networked hard drives simultaneously. (29) Let us further posit that the running of the search program would have a negligible impact on each of the individual systems, (30) and that the search program would report nothing more than the presence or absence of a given piece of digital contraband. Under this scenario, a law enforcement officer who through ordinary means discovered one copy of a piece of digital contraband -- a child porn video or a copy of WordPerfect cracked by "Captain Blood" (31) -- might infer that since one computer owner has this file, others may as well. The officer might then run a Net-wide search for that contraband. He certainly would not capture every single person who possessed it, but he might nevertheless identify dozens, hundreds, or even thousands of individuals who did have a copy on their computers and for whom he would then have probable cause to request a search warrant. (32)

*1100 The search just described presents a novel set of characteristics: (33) As part of a dragnet search, individuals' hard drives are searched without their permission and without any particularized cause to believe them guilty, and the search scans through a vast amount of very personal information located within people's offices and homes. At the same time, however, the search has a minimal impact on property, (34) produces no false positives, need not be noticeable, and reveals nothing to officials beyond the identity of some individuals who possess this particular piece of digital contraband. (35) How might the Fourth Amendment treat such a search? (36) And what does this tell us about the Fourth Amendment?