HAROLD REEVES IS AMONG THE BEST RESEARCH ASSISTANTS I HAVE HAD. HE WORKED with me to develop the first course I taught on the law of cyberspace. Early into his second year at the University of Chicago Law School, he came to me with an idea he had for a student comment—a student article that would be published in the law review. 1 The topic was trespass law in cyberspace—whether and how the law should protect owners of space in cyberspace from the kinds of intrusions that trespass law protects against in real space. His initial idea was simple: there should be no trespass law in cyberspace. 2 The law should grant "owners" of space in cyberspace no legal protection against invasion. They should be forced to fend for themselves.
Reeves's idea was a bit nutty, and in the end, I think, wrong. 3 But it contained an insight that was quite genius, and that should be central to thinking about law in cyberspace.
The idea—much more briefly and much less elegantly than Reeves has put it—is this: the question that law should ask is what means would bring about the most efficient set of protections for property interests in cyberspace. Two sorts of protections are possible. One is the traditional protection of law—the law defines a space where others should not enter and punishes people who nonetheless enter. The other protection is a fence, a technological device (a bit of code) that (among other things) blocks the unwanted from entering. In real space, of course, we have both—laws and fences that supplement law. No doubt there is some optimal mix between fences and law. Both cost money, and the return from each is not necessarily the same. From a social perspective, we would want the mix that provides optimal protection at the lowest cost. (In economics-speak, we would want a mix such that the marginal cost of an additional unit of protection is equivalent to the marginal benefit.)
The implication of this idea in real space is that it sometimes makes sense to shift the burden of protection to citizens rather than the state. If, for example, a farmer wants to store some valuable seed on a remote part of his farm, it is better for him to bear the cost of fencing in the seed than to require the police to patrol the area