I want to talk about different ministers in a government in Latin. Minister and ministra are good words for a minister, but how to say "minister of justice and employment" and "minister of economic affairs", for example? Ministers of foreign affairs appear occasionally in Nuntii Latini, and they use the expression minister a rebus exteris, and the prime minister seems to be princeps minister.
Which constructions can I use to refer to ministers? For example, are minister culturae (genitive), minister culturae (dative), minister culturalis and minister a rebus culturalibus all correct?
I have understood that in classical Latin titles typically come with datives, so I would expect minister culturae (dative, not genitive). However, at least Nuntii Latini doesn't seem to use dative here. Is abandoning the dative a post-classical thing or is it that minister requires a different construction?
Any insights to the origin and proper usage of ministers' titles are welcome.