Somewhat related to the previous post is another argument I hear from people, often in the context of gay marriage. It's the claim that we shouldn't have votes on civil rights. As nice as that sounds, it's wrong. We should vote on civil rights, and often have.
Now, there's one sense in which the people who say this are obviously right, but it can't really be what they mean. That is, we shouldn't have to vote on civil rights, because everyone ought to know what civil rights we deserve, and so it shouldn't be up for discussion. And yes, in a certain, trivial sense, everyone ought to have perfect moral knowledge, and not need to be convinced of anything, because it is right, after all. But in this sense we shouldn't have to have a government, because people ought to know which percentage of their income they need to give to public education, and all the other good works that a government does. This might be true, but only trivially so, and I assume that when people make this point they aren't making a trivial one.
This misunderstanding comes from an overblown view of what the role of judiciary is. I actually have a very favorable view of the role of the judiciary branch in government. Its purpose is to engage on particular questions of constitutionality, precedent, and reasoned argument. It will always be needed to make sense of circumstances that particular lawmakers might never have foreseen, but also to introduce a form of rigorous reasoning and reflection that might otherwise be absent from a lawmaking body that solely relied on elected officials.
But the best way to make sense of this branch of government is a working in conjunction with the legislature, not sending opinions down from on high. So if the courts decide that a certain group, for example homosexuals, have been denied civil rights to which they are entitled, this is the beginning of the dialogue and not the final word. Based on the court's interpretation of the constitution, precedent, and the legal argument, homosexuals ought to have more civil rights. If the legislature disagrees, they don't have input about the precedent or legal argument, but they can move to change the constitution. In some forms of democracy there are higher bars required to change a constitution than others, and perhaps one of these forms is more preferable than the other (your position on this will probably change based on your opinion of the judiciary.)
Or instead of going to the legislature, it might go to a referendum. You might quibble over what kind of bills should be put on the ballot or not, but I don't think you can a priori rule out all "civil rights" votes. What we're trying to decide is whether or not they should be civil rights after all! And just because we're happy with the decision of the current judges does not mean democracy stops.
Imagine, then, what would happen if the court could declare "civil rights!" and then nothing more could be said about the matter. If the opposition to the court's decision were strong enough, I think it's obvious what would happen. People would just ignore the court. And what would the court be able to do? The law enforcement is under the executive branch, and if the president sided with the majority, and decided not to listen to the court, the court wouldn't have anything else to say about it.
Why doesn't this actually happen? Because the majority of the population, to some degree at least, accepts the legitimacy of the court. If the executive branch decided to ignore the court, there would be an extreme backlash. The legislature would listen to the electorate and impeach the president. However, the only reason we see the court as legitimate is that it stays within certain bounds, and functions in tandem with the other branches. The process I described above, the checks and balances of government, are in part what gives government its legitimacy.
If you still don't agree with me, consider this. PETA (of whom I am not fond) recently brought suit to the courts claiming that killer whales ought to be considered legal persons, and thus their captivity at Seaworld was a form of slavery. I think they're right morally, but suppose the court actually decided to classify all animal ownership as slavery, and thus illegal. Obviously the legislature would amend the constitution and make it explicit that non-humans could be owned as property. But if there we weren't supposed to vote on civil rights, then the legislature wouldn't have a say in this issue. But then neither could the court, because obviously everyone would just ignore them.
The role of the people in creating laws, including laws regarding civil rights, cannot be diminished without undermining the whole system. Unfortunately, that means that people will often vote and make the wrong decision. The judiciary works as a counterbalance to the tyranny of the majority, but justice doesn't always win out.