Sadako said:
My local community college just approved my course on 'Ethics and Star Trek'.
The class is basically this: Every Thursday night, we watch an episode of Star Trek, then we talk about how that episode featured a terrible justification for the Prime Directive.
You'd find more and better examples in TNG than you would in TOS*.
*I'm assuming that by Star Trek, you're referring to the original series alone and none of its spinoffs.