While Facebook struggles with f-commerce, a younger upstart, Pinterest, may be the next big thing in social commerce. The service, which is an “online pinboard” that allows users to “share things you love”, is surging in popularity.

But there may be a downside to increased popularity, as some are questioning whether the service is promoting copyright infringement on a massive scale.

At issue: the process of ‘pinning’, which typically involves Pinterest users posting photos that they didn’t take and don’t own the rights to.

The Business Insider spoke to media law attorney Itai Maytal, who says this leaves Pinterest in questionable territory. According to Maytal, Pinterest doesn’t have a strong Fair Use defense, and while the Digital Millennium Copyright Act (DMCA) has a safe-harbor provision for internet service providers so long as they remove copyrighted material when notified, Maytal says “they’re not doing that.”

In Maytal’s estimation, “the big problem is that [Pinterest] grabs entire copyrighted works to re-post. This could be hard to overcome, especially as Pinterest starts growing and becomes more of a destination for a greater audience” although he notes that nobody will know how Pinterest’s defenses stack up until the company faces a legal challenge.

While Pinterest may not face the kind of legal opposition services like Napster and YouTube did, intellectual property rights don’t matter less because we’re dealing with photographs instead of, say, hit songs or movies. Just look at how angry individuals get when a major news organization swipes and uses a photograph without permission.

That said, given the fact that services like YouTube have been able to defend themselves in court using the DMCA, it’s hard not to think that Pinterest would be able to defend itself in a similar fashion.

The big question, however, is whether that’s the assumption the company should be making. Although Pinterest’s terms of use ask users not to upload photos they don’t have the rights to, the company must know that most users are violating this. Instead of hiding behind the DMCA, companies like Pinterest should recognize that the “we’re protected by the DMCA” defense may not last for very long and that it’s in their interest to find ways to ensure that they’re not promoting massive infringment.