In this case, the photos were owned by Playboy, the site hosting the photos were a pirate site and the website that was sued provided links to the pirated site.
After Playboy found out about what was going on, the initially send the linking site a take down notice of the links. Saying pretty much 'you are linking to a pirate site hosting our stuff, please stop.' The linking site said, 'nope we are making to much money
off of those links to take it down.' So Playboy sued.
Under any interpretation I have seen from knowledgable sources at a minimum there is a requirement that the links be to pirated data, and that the linking site knew or should have known that the links were to pirated data.
There is some question about
- the level of knowledge that can be imputed to a website based on their commercial
nature. So CruiserForum is probably (almost certainly) fine, but if you run a website that distributes links to pirated video (PirateBay) you could be hosed. Because PirateBay is in the business of distributing links to pirated videos, CR isn't.
- whether a take down notice is required in order to file suit. I tend to think it isn't required, but a very good idea. It removes the question about if the site has actual or constructive knowledge by informing them in no uncertain terms that the links are to pirated copies of the works.
As always keep in mind that European (excluding England) law is Civil not common, so court ruling are non-precedential. They may inform a later court looking at the same issue, but are not binding. This leads to looser language in court rulings than we tend to see in the US because the courts aren't as worrying about having to undo bad precedent.