Couple of questions regarding the Prime Directive:
1) Is it the Prime Directive that requires the Federation to only offer membership to worlds that have unified under a government that can represent the entire planet? 'Cause if there were still factions, then dealing with one faction or another could constitute unacceptable interference. Am I even right that there is such a rule, or does it only seem that way?
2) Isn't it a bit convenient that the Prime Directive allows the Federation to trade with worlds regardless of what kind atrocities might be happening on those worlds?