If your action requires matching or selecting a EU MEP - especially if you use tailored messaging and/or merge fields - then further testing is advised.
Why?: the wide and growing range of recipient lookup (and supression) plus message tailoring options means it is easy to have incorrect settings.
MEPs are currently matched randomly based on the selected country. Other matching methods can be added.
Test for negative results, not just for positive (e.g. specific national party/EU group member) but for results that should be negative (was a cabinet member in this/previous government, was a party member