Change in the Prime Directive between TOS and TNG?

[Kaelef]

As far as I recall, the Prime Directive only applied to less-developed (non-warp-capable) cultures in TOS. So, for example, it wouldn't apply when addressing Vulcan or Klingon culture (although, obviously, there are political and other ramifications to consider in those cases).

I've been rewatching TNG, and there have been multiple instances of anguish over the PD applying to cultures which were nearly or equivalently developed as The Federation. The most recent example I've seen was in "The Outcast" (s5e17).

Has there been discussion of this change or has it been addressed somewhere (e.g. books)? Just curious...

 

[Mojochi]

Not just having it apply to equally developed cultures, but to ones with which they already have all manner of relations, geopolitical ties, & shared interests, like Klingons & Vulcans. It does seem to be pretty unrealistic. If you can't involve yourself legitimately in a Klingon civil war, when you greatly suspect that it's being instigated by Romulans, then what good is having any alliances at all?

 

[RAMA]

It was elaborated on and expanded.

I think the key new provision: You can deal with equal races, but still cannot unilaterally interfere with them. The UFP has to let them govern themselves.

I think Gene and company saw what was happening in the world in 1986 and thought better of the USA interfering in Central Americas as well as a more advanced culture interfering in a less advanced one. It was a more mature view. The UFP was not to become the "world's policeman".

As with anything, and as established in the show itself in season 1, there are no absolutes.

RAMA