Beginning in the late 1990s, case law began to see a reemergence of an old and largely dormant tort theory, trespass to chattels, being applied to the act of wrongfully accessing a computer system. Under California law, the tort of trespass to chattels encompasses "intermeddling with or use of or damages to" personal property that does not amount to an interference with the possessory right sufficient to constitute a conversion.  

The case of eBay v. Bidder's Edge, Inc., 100 F. Supp. 2d 1058 (N.D. Cal. 2000), transported the doctrine into the digital age, allowing a preliminary injunction to be issued based on: (1) unauthorized access to eBay's system; and (2) a possibility of damage to eBay's system, stemming not only from the defendant's use but also from the potential cumulative effect caused by other hypothetical parties who might access eBay's system in a similar manner. Intel Corp. v. Hamidi, 30 Cal.4th 1342, 1347 (2003), by contrast, placed a significant limitation on the doctrine by holding that a trespass to chattels claim is not available under California law absent a showing of tangible interference to or impairment of the use or operation of a computer. ("[Trespass to chattels] does not encompass, and should not be extended to encompass, an electronic communication that neither damages the recipient computer system nor impairs its functioning"). (Emphasis added).  

In analyzing subsequent cases applying this uneasy equilibrium, significant consideration must be given to the procedural time at which the trespass issue is examined. As illustrated by the varying results in such cases as Miller v. International Business Machines Corp., No. C02-2118 MJJ, 2006 WL 2792416 (N.D. Cal. Sept. 26, 2006); Coupons, Inc. v. Stottlemire, No. CV 07-03457 HRL, 2008 WL 3245006 (N.D. Cal. July 2, 2008); and Atlantic Recording Corp. v. Serrano, No. 07-CV-1824 W(JMA), 2007 WL 4612921 (S.D. Cal. Dec. 28, 2007), courts have a demonstrable tendency to effectuate the balance between the above principles by approaching pleading stage motions somewhat leniently in considering allegations seeking to elevate computer use to computer "damage" or "impairment", but to be significantly more rigorous at the summary judgment or trial stage, there requiring a concrete showing of harm to a computer, not merely the unwelcome use of an insignificant amount of its resources. Additionally, the eBay doctrine of hypothetical damage by repeated use remains viable in an appropriate case, though the doctrine has been applied in a restricted fashion and requires a relatively narrow set of facts akin to eBay. (Principally, the injunction context and a site akin to eBay that is susceptible to robotic searching by multiple accessing parties.)  

The full text of this article, published in Intellectual Property & Technology Law Journal, Volume 21., Number I., January 2009, can be found here.