Pinterest is the internet's hottest new social-media site, logging nearly 18 million unique users in February. Pinterest members are addicted to its "Pin It" tool, which allows them to post images from the web on their virtual bulletin boards. But the rabid enthusiasm was undermined by a major reality check this month, when one Pinterest user, Kirsten Kowalski, pointed out that using other people's images could leave her vulnerable to charges of copyright infringement. Now analysts are wondering if Pinterest is the next Napster, the music-sharing site that skyrocketed in popularity, before plummeting under the weight of a slew of copyright claims. Here, a guide to Pinterest's potential legal challenges:

What did Kowalski uncover?
A lawyer with a serious photography hobby, Kowalski seems to be "the perfect combination for parsing the Pinterest problem," says Anthony Wing Kosner at Forbes. In a blog post that went viral, she revealed that Pinterest's "Terms of Use" section says users are "solely responsible for what they pin and repin," says Alyson Shontell at Business Insider. That means users are vulnerable to copyright lawsuits — much the way Napster users were during its heyday — but Pinterest itself is immune. Kowalski proceeded to "tearfully" take down her Pinterest board, fearing that she could be sued.

What does Pinterest say?
Pinterest claims that copyright law "provides safe harbors for exactly" the type of platform it offers. It also says it is committed to responding quickly to claims of copyright infringement, which is how YouTube and other content-sharing sites protect themselves from legal repercussions. Ben Silbermann, the company's chief executive, has even contacted Kowalski and asked for her input on how Pinterest can better protect its users. 

Is that enough?
Not really, some legal analysts say. For example, Pinterest openly encourages users to share "all the beautiful things you find on the web," even though the small print says you should never post anything without the owner's permission. Of particular concern are "pictures of celebrities, especially ones interacting with brands," since companies and Hollywood stars have a huge interest in protecting their images, says Henry Blodget at Business Insider

So will I be sued for using Pinterest?
"There's plenty of stuff on Pinterest that commerce companies (and others) want pinned, so we don't think the company will get sued into oblivion like, say, Napster," says Blodget. Pinterest, which is mostly popular with women, also attracts a different demographic than Napster did, and it's hard to imagine "a 39-year-old, church-going mother of three from Utah" getting sued for copyright violations, says Kosner. And Pinterest isn't worried, because, it says, "virtually every site on the web that allows users to express themselves contends with copyright complexities." Regardless, "we doubt this issue is going to quickly go away," says Blodget.

Sources: Business Insider (2), Forbes, Wall Street Journal (2), Wash. Post