This article is made available by the author under a Creative Commons Attribution license available at http://creativecommons.org/licenses/by/3.0/Digital copies of physical books and art objects curated by libraries and museums are being made available to the public online. Their access and reuse conditions are submitted to terms of use and policies defined by the institutions in charge of the development of databases and the digitisation of works, of which many are in the public domain. As no copyright applies to these works, their digital instantiation should in principle be freely accessible and reusable. However, in practice, some memory institutions databases contractual terms of use impose restrictions (for instance, reserving the commercial use of the version they digitalized or reserving the right to reuse photographies they funded), thus re-introducing physical barriers for resources which are supposed to be in the commons. The article analyzes a sample of online databases policies of libraries and museums public domain collections in various countries, and provides examples of best practices of institutions and collective actions to avoid adding unnecessary restrictions to public domain works. A good governance of the digital commons including adequate partnerships will enhance access to knowledge
