biddersedge v. ebay is particularly interesting, as is verticalone.com, now yodlee.com.
Trespass to chattels is an old roman law which dictates what should be done if you tresspass on my land and hurt one of my cattle, and it is used as the core of most cases involving scraping in unauthenticated environments (like Y! finance). They can come get you, not for taking data, but for costing them money to support the response volumes you demand. The magic number is $5,000, at which time it becomes a felony (or at least that was the threatening rhetoric, which is a different story altogether). You scrape, hurt their cow for 5k, and it is not a question of restitution, but of punishment. And in each case the scraper is typically viewed as a "thief"... not a label that inspires lighter punishments. see:www.biddersedge.com, yeah, exactly. nuked from orbit... and there, in a nutshell, is the risk inherent in scraping. All a scrapee has to do is wait for you to pass $5k... while they consider the pr ramifications of the whole thing... how much bandwidth and resources need to be used before the public will sympathize? 10k? 20k? 30k before they are lauded as a hero for removing the thieving vermin?
Insidious really, scraping and scrapers are being "set up the bomb" here... to not be viewed as enabling the liberation of data, but rather as thieves of the resources necessary to deliver that data to the general public. Using trespass to chattels as a precedent is therefore a brilliant stroke... apparently, they can be taught. Or, to put it another way, scrapers aren't napster users in dorm rooms, they are felony thieves of public resources.
Yeah, we all know that cease and desist and all other legal remedies are jurisdictionally challenged - the net doesn’t stop at international borders. And, historically, it seems that other countries turn a deaf ear to most cyber crime excepting, of course, for credit card fraud.
Also, limit scraping via tor. Tor has a legitimate use which scraper volumes would impact. Of course, there are tor nets set up for "illegitimate" use... and they let anybody in, including folks like me, who then map all tor exit nodes used by scrapers and interdict em all...
And, don't forget steganography... you take data (even through tor or rotating proxies) and redisplay it, google can find it and I can ask google to tell me where it is. Scrapers, even as very clever data middlemen, will get the squeeze from both sides as scrapees discover where their data is being displayed and utilize legal means to go after those storefronts, who will of course first provide name, rank and serial number of the scraper that provided them the data...
And what about copyrights? Lots of legal precedent here, be careful with image redisplay. Mine field here...