Why are there so many different models of e-lending in Europe? Is it possible to envisage a uniformity of practices and solutions in this disparate landscape? And what are the respective roles of public authorities and of public libraries in this field? Despite the progressive development of the e-book offer, libraries still encounter many difficulties in implementing e-lending. Those difficulties are of a variable nature – legal, technical, and financial. For some expert librarians, e-lending is mainly considered under a legal perspective, where the recognition of the derogatory status of digital library transactions in relation to copyright laws legitimises open access practices through customary fair use. A valuable approach, this methodology has nevertheless some limits: in the European copyright system judges do not have the same latitude in interpreting the law as in the Anglo-Saxon system, where the right of access to digital publications is based on fair use. On the other hand, the judgement of the Court of Justice of the European Union (in the case opposing the Dutch Library Association to the Leenrecht Foundation, case C-174/15) made an important step towards the development of e-lending in libraries. The CJEU ruled that library lending of e-books is analogue to the lending of printed books, under certain conditions. Any legal reflection around e-lending should therefore revolve about two principles: on the one hand, the principle of free access to information which is essential for the functioning of libraries, and on the other hand the principle of appropriate remuneration to authors. This balance is what EBLIDA calls: sustainable copyright. Merely legal considerations, however, are analytically limited and do not help find appropriate solutions to the problem raised in libraries. The institutional background and the economic environment surrounding e-lending include the number of transactions of e-books in libraries, the content of the policy of public powers, the nature of the e-book trade (e.g. the popularity of e-books among young people), the practices linked to e-book acquisitions in libraries and the quality of publishers-libraries interrelation. All these factors are determinant in the structure of an e-book economy. This holistic approach – legal, economic, institutional – has often been neglected in professional library circles as well as in sectorial studies. The EBLIDA survey on e-lending in the context of the book economy, whose results will be known in Spring 2022, has the general objective to lay the foundation of a “sustainable copyright” in public libraries through the examination of three particular aspects: The dependence of the e-book library trade and library acquisitions on national economic factors, legal constraints and institutional requirements (number of users, percentage of publications available in a digital format, purchasing power of libraries, the role of intermediate layers negotiating with publishers on behalf of libraries) The role played by national public authorities in the choice of an e-lending model The potential strength of a networked system where the library demand is aggregated, with an active e-book cultural policy carried out by libraries.