How about one on the Prime Directive, It fairly obvious that it hasn't existed since the beginning of the Federation. First half of TOS might have had no PD at all. It also seems to have changed over time, either through politics or maybe simple practicalities.
How about 'how does the process of joining the Federation go?' Or even more precise 'how does the new member's military get absorbed/integrated into Starfleet?'
I love both of these ideas, but have no bloody clue
where to begin with either!
That said, something unrelated to the above but relevant to the general thing.
General rules of thumb for Penta's worldbuilding threads:
1. I tend to set myself just ahead of the canon timeline - which, in the case of post-NEM, has generally meant about 2383-2385, a perspective I plan on sticking with because we saw so damn little of 2387. The reason for this is because I am the first to admit my grasp of canon can sometimes be shaky. It's best for TNG through ENT, but is very weak, practically non-existent, for TOS (I just haven't gotten myself to look past the 60s production values amd really watch TOS); Also, it enables me to 'shape to taste': a great example of this came in my Starfleet Academy thread.
We know damn little by canon about SFA. How you design SFA, though, impacts (and is impacted by) directly on how you think about Starfleet. My view of Starfleet has always been, as befits the RPG/gaming perspective from which I tend to deal with Trek, more militarized than canon might suggest at first glance, which influenced a lot of how I designed the academy. I see Starfleet as an organization that has struggled and waffled over how to define itself, always at tension between its military and scientific heritages, until the Cardassian and Dominion Wars forced it to firmly see itself as, first and foremost, the Federation military. Someone who thinks of Starfleet as more of a scientific organization even after the Dominion War would design Starfleet Academy, and hence Starfleet, rather differently.
2. Before I embark on any worldbuilding thread, I lay out my "modelling assumptions" explicitly. Arguing on these is...not really advised; I'm not a mod, so I can't and won't say you can't argue them, but I will ask that you respect the "ground rules" and accept the modelling assumptions as posited, unless I'm firmly missing something. I know
they're arguable points, but that's why I call them modelling assumptions: They're things I feel have to be defined in order for me to go from the amorphous, inconsistent blob that is Trek canon to the concrete detail that these threads are best at and that is the real value of these threads. Hence, arguing with the modelling assumptions in a thread tends to just make me grouchy and irritable. I am not
infallible, I do not even begin to claim infallibility or inerrancy, and I welcome competing ideas. If you're convincing enough, you can overcome my natural stubbornness and change my mind or at least force me to explain myself; T'Girl and Neozeks, most notably among others, have done so in the past (sometimes exceptionally well). That said, I ask respectfully that full-fledged competing worldbuilding happen on other threads, to make things easier for the reader.
3. My threads do not intentionally build on one another, but they do tend to refer to and inform one another. I'll use concepts generated in my thread postulating a Starfleet Command structure to inform my thinking on Federation government, as well as my thread on Starfleet Academy, and my thread on colonization, and so forth. If you need links to previous threads, PM me if you can't find them through other means (though you should be able to). If someone is willing to help someone with zero web design skills (or if the mods would be willing to allow me a thread for the purpose that I could quote in my sig), I would one day love to get links to all the threads in one place.
4. While I set my perspective 'beyond the canon', I try to write worldbuilding that could be applicable to any era of Trek in the prime universe. That, plus the greater traffic, is why I post these threads to GTD, not to a series-specific forum or Trek tech or somewhere.
5. My pieces are not in-character documents, as a rule. They generally are out-of-character; I will, however, make extensive use of bracketed ('s) "margin notes" to explain things, add detail or additional stuff that doesn't fit elsewhere, or explain how known something is "in-universe", IMHO.