and use the works of that creator as though a government had legally confiscated their physical possessions after a set period of time. Society as a whole is granted the same right to appreciate and exploit the property that once was under the exclusive control of a single family or corporate entity. This wider potential for the creative exploitation of works formerly under the exclusive control of a copyright owner promotes learning. Public Knowledge and other critics wrote that existing copyright terms already provide more than sufficient compensation for creators of intellectual property. It has also been argued that copyright should not become a welfare system used to benefit remote descendants who happen to come into possession of a valuable copyright through the lottery of birth, and that society is a "quite important heir" to copyrighted works. Critics of perpetual copyright also point out that creative activity often involves the creation of derivative works that recast or build upon previous material. If this prior material were perpetually copyrighted, their respective copyright holders would have the indefinite right to license their intellectual property or deny its use as they see fit. Many new derivative works could not be produced if the interested parties were denied permission or could not afford the licensing fees. Moreover, the longer copyright persists, the more copyrighted material falls into the category of orphan works. Anyone seeking to create derivative works based upon orphan works faces the risk of copyright infringement if the copyright holders were to come forward at some later time to enforce their rights. Perpetual copyright would create a significant disincentive to the creation of new literary or artistic works which build upon older material. Battle of the booksellers When the statutory copyright term provided for by the Statute of Anne, the first copyright statute, began to expire in 1731 London booksellers fought to defend their dominant position by seeking injunctions from the Court of Chancery for works by authors that fell outside the statute's protection. At the same time the London booksellers lobbied parliament to extend the copyright term provided by the Statute of Anne. Eventually, in a case known as Midwinter v Hamilton (1743–1748), the London booksellers turned to common law and started a 30-year period known as the battle of the booksellers. The battle of the booksellers saw London booksellers locking horns with the newly emerging Scottish book trade over the