I have a project licensed under the EUPLv1.2 license, and I want to incorporate GPLv3-licensed code in it. However, due to the GPL's copyleft, that is not legally possible.
Is it possible to dual-license the project with both licenses (EUPLv1.2 and GPLv3) to allow for the GPLv3-licensed code to be incorporated in it, despite incompatibility with EUPLv1.2?
I have a project licensed under the EUPLv1.2 license, and I want to incorporate GPLv3-licensed code in it. However, due to the GPL's copyleft, that is not legally possible.
It is not legally possible to distribute the resulting derived work under the EUPLv1.2 license, because the GPLv3 license does not allow that. However, it is possible to distribute the resulting derived work under the GPLv3 license.
If you are the (sole) copyright owner of the EUPL work, then you always have the possibility to change the license, but even if you are not the copyright owner, the EUPL allows you to change the license to an enumerated set of other licenses and the GPL happens to be on that list.
Is it possible to dual-license the project with both licenses (EUPLv1.2 and GPLv3) to allow for the GPLv3-licensed code to be incorporated in it, despite incompatibility with EUPLv1.2?
No. Dual licensing gives the recipients of your code a choice which license terms they want to follow, but it does not help you to get around license incompatibilities.
Technically, you could dual-license the project (assuming you are the copyright holder of the EUPL code), but effectively your users would only be able to choose to follow the GPL license due to the dependency on the GPL code.
It is possible to incorporate GPL v3-licensed code in a project released under the EUPL v1.2.
Assuming that you are not the creator of the EUPL v1.2 license and are creating a derivative work, Clause 5 of the EUPL states that if you create a derivative work by combining the EUPL work and a work under a Compatible License, you can release your derivative work under the Compatible License. GPL v3 is one of the Compatible Licenses listed in the EUPL. Because of the attribution obligations, anyone receiving your derivative work would have a pointer back to the original EUPL work if the GPL is not acceptable and they would be able to use the original project or create a new derivative work that is suitable for their use.
If you are the creator of the EUPL v1.2 license, then you won't be able to dual-license the work. A dual license allows the recipient to choose which terms they want to accept. If someone chooses the EUPL license, it appears they wouldn't meet the GPL's requirements for a derivative work. You would have to change the license for the version that includes the GPL work. If you have received contributions from others, this may get more difficult.
