The quick rise of the social-networking site Pinterest has summoned up a host of new questions about the legality of the content that its users – more than 10 million registered in all – are posting across the site in droves. In other words, what does one do with all the copyrighted material being shared across the site?

While Pinterest has attempted to solve the problem on its end by giving publishers a means to flag and report content for removal, that's an awfully ambitious undertaking, especially when the content being shared has been curated from other giant social networks. How might a typical Flickr user even go about finding and flagging images that he or she doesn't want shared, for example?

In this case, Yahoo's photo-sharing site chose to adopt Pinterest's most recently announced feature, which we're calling the "Pinterest Kill Switch." It comes in the form of a small piece of HTML code that can be added to any website. In doing so, an author blocks users from being able to "pin," or picture-bookmark, any content on the site.

"Flickr has implemented the tag and it appears on all non-public/non-safe pages, as well as when a member has disabled sharing of their Flickr content," a Flickr representative said an in interview with VentureBeat's Jennifer Van Grove on Friday. "This means only content that is 'safe,' 'public' and has the sharing button enabled can be pinned to Pinterest."

But does this measure effectively prevent any user from sharing any Flickr content on Pinterest? No. Ambitious users can still screen-grab an image they like and upload it to Pinterest manually, much like users can still acquire photographs or images on which Flickr photographers have otherwise disabled downloading – same deal.

And the jury's still out – not literally, we note – on whether Pinterest itself would even be subject to any legal problems should a person or corporation head to the courts regarding copyrighted work being shared on the site.

"For Pinterest, the legal issues are not cut and dry. On one hand, its notification scheme should grant it a 'safe harbor' under copyright law. It is this law that protects sites like Facebook or YouTube from being sued when a user uploads copyrighted material," paidContent's Jeff Roberts writes.

"But on the other hand, Pinterest's business is based almost entirely on using images without permission—something that could lead it to lose its safe harbor protection in the same way that Grokster did," he said.

For more, see PCMag's full review of Pinterest and the slideshow above.

For more from David, follow him on Facebook or Twitter (@thedavidmurphy).