There are some European countries which want to become EU members but EU says they need to do more efforts to defeat corruption before they will be accepted. For example Moldova and some other countries. Possibly one way for them to defeat corruption could be creation of some kind of "European Police" and open offices of Europol in many Moldovian towns. Under this program police officers from Western European countries as well as judges and prosecutors will be permitted to conduct investigations, arrests and cort processes on Moldovan territory. For example if some Moldovan citizen suspects that local police doesn't want to do arrests and investigation because of corruption or some Moldovian judge rulled out an unfair decision he may ask for help the nearest division of European Police or European Court in Moldova. For this EU law and EU police power suppose to have prevalence of law over Moldovan law and police. I guess majority of population in Moldova would gladly support such an innovation. If countries purchase a lot of goods and services from other countries, why cannot they buy law inforcement services? EU already has the principle about prevalence of EU law over national law of the member countries. So, if Moldova wants to become a member, why not accept this principle right now? Otherwise these countries could wait entire generations before they will become EU members.
EUR-Lex - primacy_of_eu_law - EN - EUR-Lex (europa.eu)The principle of the primacy (also referred to as ‘precedence’) of EU law is based on the idea that where a conflict arises between an aspect of EU law and an aspect of law in an EU country (national law), EU law will prevail.