The case of Intel v. Hamidi has been going on for a few years now, and it's now reached the California Supreme Court. Hamidi is an ex-Intel employee with a grievance against the company who sent several mass-emails to most of Intel's staff. Intel attempted to block him from sending email via technical measures, and when that failed filed suit against him claiming that he was causing some harm to their property (company mail servers and computers) - there's an ancient legal concept called "trespass to chattels" which Intel is attempting to use in their case. Now, in real-dollar terms, Intel has suffered very little - a few megabytes of email more or less is a miniscule cost in terms of computer wear and tear, indeed, too small to measure (Intel is not alleging that Hamidi sent any sort of mail-bomb or that his emails caused damage). So the case comes down to an unsettled legal point: if someone has made some use of your electronic equipment, which you may not have desired but which has not damaged your property nor deprived you of its use, do you have a legal cause of action against them?