It set up a perfect natural experiment

To address these empirical challenges, this article exploits an unanticipated and unintended differential increase in the length of copyrights—from low levels of existing copyright lengths. In 1814, Britain’s Parliament passed the Copyright Act to clarify a requirement to deposit copyrighted books with research libraries. Due to the timely and opportunistic intervention of a member of parliament, however, who was also an author, the law also extended the length of copyrights in an unusual way. Until 1814, the length of copyright was 14 years (starting from the first edition) for books whose authors had died within 14 years since the first edition, and 28 years for books whose authors had survived the first 14 years. After 1814, copyright length increased from 14 to 28 years for books whose authors had died within 14 years since the first edition, and from 28 years to author’s remaining years of life for books whose authors had survived the 14-year term. Given the life expectancies of romantic period authors, this change created no meaningful increase in copyright length for living authors, but it created a 14-year extension for books by dead authors.5

Our empirical design takes advantage of this differential increase in copyright length to compare changes in price after 1814 for books by dead and living authors. This difference-indifferences approach allows us to control for unobservable factors that may have changed the price of all books after 1814, irrespective of changes in copyright length. For example, books may have become more expensive after 1814 because the demand for reading increased with improvements in literacy. Book prices may also have declined as a result of technological progress that reduced production costs, for example, through the diffusion of continuous papermaking andsteam-powered printing.6 An additional benefit of our approach is that death is easily observable, whereas other proxies for the remaining length of copyright are subject to measurement error.7

Unique historical data for 1,227 book editions published between 1790 and 1840 allow us to examine changes in price for recently published copyrighted books. These data include 989 editions of titles that were less than 14 years old, and therefore still on copyright and affected by the increase in copyright length. We have collected price information for these books from romantic period book catalogues, including the London Catalogue of Books (Brown, John’sSquare, and Clerkenwell, 1799; Hodgson, 1855) and the English Catalogue of Books (Peddie and Waddington, 1914), and from The Reading Nation in the Romantic Period (St. Clair, 2004). For each of these editions, we construct controls for the age of the book, author fixed effects, physical characteristics (counts of volumes, page counts, and page size), and genre (novels, poetry, other fiction, and nonfiction).8 To proxy literary quality, we match editions in our data with records of notable books: Western Canon (Bloom, 1994), Greatest Books (Sherman, 2009), and Norton Anthology of English Literature (Greenblatt and Abrams, 2012).