https://www.wto.org/english/tratop_e/dispu_e/dispu_by_country_e.htm
I was looking at this and it seems European countries are sometimes respondent to WTO disputes, and not the EU as a whole, so I was wondering if the EU has some kind of mechanism to handle these cases before they are brought by the WTO, because I didn't see any European country complain against another European country at the WTO.