- with American and Common Law concepts and terms such as "copyright" translated to concepts meaningful in the EU
- covering "moral rights" (like German UrhG law which has certain rights that you can't transfer at all, such as claiming to be the author of something)
- avoiding overly broad (and hence void) non-liability provisions
- with provision to determine the venue/court to bring cases to.
The EUPL has provisions to integrate EUPL-licensed works into other works and for relicensing under more liberal/non-copyleft licenses, but the cavalier attitude when it comes to copyleft makes it unclear to me whether the EUPL actually is a strong copyleft license (cf what the FSF says about it [2]).
[1]: https://joinup.ec.europa.eu/community/eupl/og_page/eupl
[2]: https://joinup.ec.europa.eu/community/eupl/news/new-fsf-stat...