The (2017) EUPL-1.2 compatibility clause is as follow:
"If the Licensee Distributes or Communicates Derivative Works or copies thereof based upon both the Work and another work licensed under a Compatible Licence, this Distribution or Communication can be done under the terms of this Compatible Licence. For the sake of this clause, ‘Compatible Licence’ refers to the licences listed in the appendix attached to this Licence. Should the Licensee's obligations under the Compatible Licence conflict with his/her obligations under this Licence, the obligations of the Compatible Licence shall prevail."
When thinking to update the EUPL (enlarging the list of compatible licenses i.e. to new ESA licenses) the compatibility clause may warrant clarification, not a change: some have questioned whether there is a risk of circumventing network distribution (or SaaS) coverage. The new wording could be as follows (but any suggestion for improvement and brevity would be welcome):
"If the Licensee Distributes or Communicates Derivative Works or copies thereof based upon both the Work and another work already licensed under a Compatible Licence this can be done, in so far the Compatible license imposes to do so, under the terms of this ‘Compatible Licence’, which refers to the licences listed in the appendix attached to this Licence. Should the Licensee's obligations under the Compatible Licence conflict with his/her obligations under this Licence, the obligations of the compatible license shall prevail, provided that the rights granted for in Articles 2 and 3 of this License, as well as its definition of ‘Distribution or Communication to the public’, are not considered as invalid further restrictions. This clause applies to the specific derivative work only and may not be used for the purpose of relicensing the original work."
When thinking to update the EUPL (enlarging the list of compatible licenses i.e. to new ESA licenses) the compatibility clause may warrant clarification, not a change: some have questioned whether there is a risk of circumventing network distribution (or SaaS) coverage. The new wording could be as follows (but any suggestion for improvement and brevity would be welcome):
"If the Licensee Distributes or Communicates Derivative Works or copies thereof based upon both the Work and another work already licensed under a Compatible Licence this can be done, in so far the Compatible license imposes to do so, under the terms of this ‘Compatible Licence’, which refers to the licences listed in the appendix attached to this Licence. Should the Licensee's obligations under the Compatible Licence conflict with his/her obligations under this Licence, the obligations of the compatible license shall prevail, provided that the rights granted for in Articles 2 and 3 of this License, as well as its definition of ‘Distribution or Communication to the public’, are not considered as invalid further restrictions. This clause applies to the specific derivative work only and may not be used for the purpose of relicensing the original work."
Thanks for comments!