with. The vast majority of in-copyright books are out-of-print or out-of-commerce, and most 
are not actively managed by their rightsholders. There is no o ﬃcial registry of copyrighted 
works and their owners, and existing datasets can be incomplete or erroneous.   16
As a result, there may be no way to license the vast majority of in-copyright books, especially 
those that have or have had limited commercial value.  Put differently, the barrier to using 17
most books is not simply to pay publishers; even if one had signi ﬁcant ﬁnancial resources, 
licensing would not enable access to most works. 
Permissively licensed works 
There are books that have been permissively licensed in an easily identi ﬁable way, such as 
works placed under Creative Commons (CC) licenses. Such works explicitly allow particular 
uses of works subject to various responsibilities (e.g., requiring attribution by the user in their 
follow-on use).  
While such works could be candidates for inclusion in a books data commons, their inclusion 
depends on whether the license’s terms can be complied with in the context of AI training. 
For instance, in the context of CC licensed works, there are requirements for proper 
attribution across all licenses (the CC tools Public Domain Dedication (CC0) and Public 
Domain Mark (PDM) are not licenses and do not require attribution).  18
 See e.g. Heald, Paul J. “How Copyright Makes Books and Music Disappear (and How Secondary 16
Liability Rules Help Resurrect Old Songs).” Illinois Program in Law, Behavior and Social Science Paper 
No. LBSS14-07 Illinois Public Law Research Paper No. 13-54 https://doi.org/10.2139/ssrn.2290181. 
Accessed 4 Jan. 2020, at https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2290181; Rosen, 
Rebecca J. “Why Are so Few Books from the 20th Century Available as Ebooks?” The Atlantic, 18 Mar. 
2014, www.theatlantic.com/business/archive/2014/03/why-are-so-few-books-from-the-20th-century-
available-as-ebooks/284486/. See also “Google Book Search Settlement and Access to Out of Print 
Books.” Google Public Policy Blog, publicpolicy.googleblog.com/2009/06/google-book-search-
settlement-and.html. Accessed 20 Mar. 2024 (discussing this issue in the context of the failed class-
action settlement between Google, the Authors Guild, and the Association of American Publishers). 
Google’s ﬁnal brief in the settlement proceedings notes the “prohibitive transaction costs of identifying 
and locating individual Rightsholders of these largely older, out-of-print books” — see this brief at https://
web.archive.org/web/20130112060651/http://thepublicindex.org/docs/amended_settlement/
google_ﬁnal_approval_support.pdf. The Authors Guild and Association of American Publishers also 
justiﬁed the settlement’s terms in light of the fact that “the transaction costs involved in ﬁnding 
copyright owners and clearing the rights are too high”; while they argued that most works are not truly 
“orphans,” they note that total transaction costs as a whole (including, for example, determining whether 
the author or publisher holds the rights and then negotiating rates) are so high as to block uses of out-
of-print works anyway — see this brief at https://web.archive.org/web/20130112060213/http://
thepublicindex.org/docs/amended_settlement/Supplemental_memorandum_of_law.pdf. 
 In the EU, the 2019 Copyright Directive introduced speciﬁc provisions on the "use of out-of-commerce 17
works and other subject matter by cultural heritage institutions" (Articles 8-11 CDSMD). These 
provisions allow cultural heritage institutions to "make available, for non-commercial purposes, out-of-
commerce works or other subject matter permanently in their collections". The limitation to non-
commercial purposes means that works made available under these provisions would be of limited use 
in building a books data commons.
 For one assessment of the diﬃculties of complying with the CC licenses in this context, to the extent 18