European Union Public Licence - An Overview

by Rowan Wilson on 2 August 2011 , last updated


Version 1.1 of the European Union Public Licence (EUPL) was approved by the Open Source Initiative on 4 March 2009. It is a ‘copyleft’ licence drafted to be fully compatible with European law. It grew from work done as part of the European Union’s 2004 IDABC programme (Interoperable Delivery of European eGovernment Services to public Administrations, Businesses and Citizens). The licence in its twenty two translations can be read at

History of the EUPL

The IDABC programme that produced the original EUPL aimed to stimulate the development of interoperable online delivery platforms for public services in the European Union. This was intended not only to help the EU’s citizens but also to make public service delivery more uniform across the Union. This in turn was intended to make it easier for individuals to work anywhere they chose, and encourage companies to invest in multi-site European installations.

Given these aims it made sense that the software solutions generated by the programme should be shared as widely as possible. Free or open source software (FOSS) licensing seemed like a good way to achieve this. However, many lawyers in Europe were cautious about the American roots of the FOSS licences available at that time. They foresaw issues with their enforceability under European law. For example many argued that the ‘No Warranty’ clauses in commonly-used FOSS licences such as the GNU GPL were null and void in many European jurisdictions as they sought to exclude damages suffered by individual consumers.

It was one of the funding conditions of the programme that any software outputs should belong to the EU itself. Thus the EU would have be the licensor of any resulting FOSS projects. Politically it would be awkward for the EU to use US licences of - some argued - questionable enforceability in their own back garden, so it became clear that a European-born FOSS licence might be needed.

In fact, as the programme was starting out, a new European FOSS licence was published by a group of three French research institutions. CeCILL - CEA CNRS INRIA Logiciel Libre - was a ‘copyleft’ licence (meaning that works that contained code it covered must also be CeCILL-licensed) written to operate under French law. It included a provision that allowed the distribution of its within code covered by the GNU GPL, making it explicitly compatible with this popular licence. While it would prove useful for its originators, CeCILL had the issue that it specified the Paris courts as the venue for any litigation on the licence’s meaning and effect. While this made perfect sense for its originators, it hampered the perception of the licence as genuinely international. CeCILL v1 was also only available in French, with an informal English translation. Version 2 of CeCILL - released in 2006 - fixed this problem by providing an official English version, as well as updating the GNU GPL-compatibility to recognise and handle the imminent release of version 3 of the GPL.

In 2007, the European Commission took on the enormous task of producing a licence based upon CeCILL that would have identically-operating versions available in all the languages within the Union. The licence is stewarded by another output of the IDABC programme, the Open Source Observatory and Repository (OSOR). In 2009, OSOR released v1.1 of the EUPL, which among other small changes closed the so-called ‘Application Service Providers Loophole’ which previously allowed licensees who based a network service on the code but did not distribute the software itself to avoid making the source code to their version available1. Also in 2009 the Open Source Initiative accredited the licence as officially compliant with the Open Source Definition.

Main Features of the EUPL

The EUPL is intended to be a copyleft licence which is fully compatible with European law. The jurisdiction governing the licence is automatically set to be that of the licensor. Issues such as what constitutes a work ‘based upon’ the covered work are also explicitly delegated to the national jurisdiction of the licensor.

The EUPL’s copyleft provision is ‘strong’ - meaning that it covers any work that is ‘based upon’ its covered code without arbitrary limitation. However it also allows its covered code to be incorporated into projects under a specific set of other FOSS licences (GNU GPLv2, Open Software License v2.1 and v3.0, Common Public License v1.0, Eclipse Public License v1.0, CeCILL v2.0), thereby ensuring compatibility with those licences. This also means that, uniquely, code under the EUPL v1.1 effectively has variable copyleft strength, depending upon whether it is taken up under the strong copyleft of the EUPL or distributed within a larger work under the weaker copyleft of the Common Public License or the Eclipse Public License.

While the GNU GPL v3 is not on the EUPL compatibility clause list, it is in theory possible to place code under the EUPL v1.1 in a GNU GPL v3-licensed project and distribute the combination under the GNU GPLv3. This can happen by the roundabout route of distributing EUPL v1.1 code under CeCILL v2.0 via the EUPL’s compatibility clause, and then distributing the resulting CeCILL 2.0 code under GNU GPL v3 under the compatibility clause of the CeCILL v2.0.

Unusually for a FOSS licence, the EUPL v1.1 provides a warranty from each licensor guaranteeing that their contribution is either their own property or licensed from a third party in such a way as to be distributable within the EUPL software in question. This could potentially make code under the licence more appealing for use within corporate environments (one of the aims of the sponsoring EU programme). However it should be noted that this also exposes a licensor making their code available under the EUPL v1.1 to greater risk than a standard FOSS licence without such a warranty.

What makes the EUPL different?

These bullet points are intended to summarise what is distinct about the EUPL. They are not intended as a full description of its features. The European Union Public Licence:

  • is available as a working licence in 22 languages
  • is drafted to work under European law
  • allows code it covers to be distributed in a larger work under a selection of other licences and therefore
  • effectively has a variable level of ‘copyleft strength’
  • offers a warranty relating to copyright from each licensorThe EUPL is chiefly used on the outputs from the IDABC programme, but is drafted to make it usable by any FOSS author.

OSS Watch has produced a document that highlights the main legal issues to consider when making your code available under an open source licence.

Further reading


Related information from OSS Watch:

  1. In fact the CeCILL licences v1 and v2 also both seek to achieve this aim according to the author’s FAQ, but in far less specific language than the EUPL v1.1