While the battles over online movie and music piracy have grabbed headlines recently, the rapid evolution of the e-book business could soon provoke new fights over copyright in the digital age. Lending libraries, at least in the U.S., have long operated under the protection of the so-called first-sale doctrine in copyright law, which allows libraries, like anyone else, to loan out copies of books they have purchased without needing authorization from the copy right owner. As with all copyrighted material on digital platforms, however, e-books occupy murky ground with respect to the first-sale doctrine. Now, with different publishers trying to impose different rules on libraries for e-books, or refusing to sell e-books to libraries altogether, tensions are starting to come to a head. Meanwhile, new types of e-books, such as the active-content apps being introduced by Amazon.com for the Kindle, are likely to raise their own questions about ownership that the current law is ill-equipped to answer.