I like the ebook DRM scheme best where they put something like "Personal copy of “buyer’s name” into the book, right next to the page numbers in the page footer. This doesn’t involve cumbersome crypto DRM that requires special plug-ins or readers to access and makes the buyer aware of the added risk of sharing his copy with others.
It makes the buyer aware that he owns a personally licensed copy and it creates some level of burden to remove this visible watermark before sharing his copy.
Still there are legal ways to share ebooks (let’s say, lend your ebook reader device to a friend) and just locating someone’s copy circulating on the net shouldn’t be grounds for suing. In other words: such DRM schemes should not put the buyer in the position where he has to prove that he did not willfully make the copyrighted works available for download.
