"Data and databases are a complex, nuanced area within intellectual property law. In the European Union databases have a special legal treatment that provides two levels of protection. A database is protected by copyright in the classical sense when it can be considered an intellectual work with a creative nature. Where databases represent mere collections of data without sufficient creativity to trigger copyright, EU jurisdictions protect the database under sui generis rights when substantial investment has been made in obtaining, verifying, or presenting the database contents according to Directive 96/9/EC. This system creates a substantial discrepancy between the situation of European countries and the rest of the world, and also affects those databases that have been released under open licenses. Not all of the currently available open licenses take account of the legal and practical implications of this discrepancy, and we should examine the consequences and options. The paper aims to provide a high-level analysis on the protection of databases under European law and identify the main legal problems arising from it in an open data scenario. Then it will focus on the solutions tried so far to implement a proper open licensing framework for the database (with an introduction to the licenses offered by Creative Commons and the Open Data Commons project). Finally, some of the most prominent use cases of open licensing for data will be analysed (such as those of geo-data and linked-data), with some observations on the modus operandi of the various promoters of projects."