|You know it makes sense|
The world of Star Trek is one in which people no longer work for gain. There's no money. How the economy works is an interesting question. Here however I want to look at the other aspects of the Federation's society.
Firstly, it has to be noted that Star Trek was not entirely clear about the degree of central authority in the United Federation of Planets. Member planets seem to have a very high level of autonomy. There is a Federation Council, referred to in TOS, but is the Federation a federation like the United States, or a body like the European Union where authority is pooled? It is left vague how the Council works: in "Amok Time" (TOS) we are told that T'Pau is "the only person ever to turn down a seat on the Federation Council" which suggests it is not simply elected. Later a President appears. The Federation is apparently democratic, but its politics centres on a Council representing planets, and we don't see much sign of anything like party politics. Basic principles are agreed: the society is based on liberal values similar to the ideals of the modern democratic world. These are not significantly different from those of now, and emphasise freedom and equality.
If the Federation is a democracy, what would politics be about? Since there are no economic conflicts any more, there would not be parties based on economic interests. In fact, this seems to apply more generally: fundamental political conflicts are finished because there is nothing for them to be about. There is no competition for wealth, and nations have united. The Federation is not heaven on earth, and it should be remembered that apparent paradises, when encountered by Star Trek, always turn out to be false (for example "The Apple," TOS). But neither is it simply a better society.
It seems that no serious alternative to the Federation's ideas is on offer for humanity. Internal threats from militarist conspirators appear, notably in DS9, but they do not represent ideologies. The exceptions are all marginal. In "Let He Who is Without Sin" (DS9), the "New Essentialist" group believes the Federation has become decadent, and sabotages the pleasure-planet of Risa. This implies a Puritanical challenge to the individual freedom of the Federation, but it seems the challenge is about social values rather than political rights, and it remains within the basic framework of the Federation's nature. Otherwise, dissidents are mainly seeking escape, apparently most often as simple-life colonists, and even they seem to accept the Federation's basic values.
In the Deep Space Nine episode "For the Cause," a Federation officer who has joined the Maquis (a group of rebel colonists and Starfleet officers) offers an interesting critique, arguing that the Federation is so implacably opposed to them because "we've left the Federation, and that's the one thing you can't accept. Nobody leaves paradise. Everyone should want to be in the Federation." Unlike the Borg, with their open threats, "You assimilate people and they don't even know it." But the Maquis do not really have an alternative. They left because, as they see it, the Federation betrayed them. They are at root disillusioned Federationers.
One area of conflict we do see is controversy about the rights of artificial life-forms. Data is ordered to submit to disassembly by a cybernetics researcher, Commander Maddox, and when he refuses he is declared to be property. ("The Measure of a Man" TNG). This leads to a courtroom scene. The question of why this wasn't settled when he first appeared, or joined Starfleet, is glossed over. In Voyager the questions arise about the Doctor, who becomes a champion of rights for holograms. His case is in some ways more interesting because there are lots of other characters in the holodeck who seem to be conscious, but are generally thought not to be (even by the Doctor). Is the Doctor real?
In principle, these cases aren't disputes about the Federation's principles, but about what category applies to certain beings. No-one is arguing that Data is alive but shouldn't be treated as such. However, as in real life, you get the impression that some people want to categorize according to their convenience. It would so convenient for Maddox if Data is not really alive. What a curious coincidence that he concludes that Data isn't.
As several writers have pointed out, the legal process depicted in Star Trek is chaotic even allowing for the "frontier" situation. It is designed to fit the various stories, and you're supposed to be following the issues being disputed. (For example, the proceedings in "The Measure of a Man" are bizarre in so many ways you will lose count if you start worrying about it.) A coherent legal system would almost inevitably be too slow to fit neatly into an episode. It would also be too boring.
 There are also oddities which seem to reflect the American perspective. In "The Mind's Eye" (TNG), when the Klingon Ambassador is unmasked as the villain, the Klingons are going to take him off the Enterprise, and he appeals to Captain Picard for asylum. Picard replies "I will certainly grant you asylum, when you have been absolved of this crime." He is, of course, unlikely to survive. In the present world, countries with no death penalty commonly refuse to hand over prisoners accused of capital crimes without guarantees they will not be executed. Is the Federation less scrupulous than ordinary twentieth-century states? Probably the writers were simply unaware of the principle. [Return]