There are two types of “ought” in US Law. The first type is in reference stare decisis and precedent: if a previous decision handled a situation in manner X, then a similar situation should also be handled in manner X because of that previous decision. For areas of law without a clear and certain statute, this is the essence of how legal issues are decided. (It is called “Common Law.”)
The second type of “ought” is the normative, moral ought we often when discussing law: the government ought to adopt policy X, because it is good for the economy; the court ought to decide the case in manner X because it is the right way to treat people’s property rights. It is based in our sense of right and wrong, good or bad, and not in what has previously been decided or enacted (unless, by coincidence, we base our sense of good and bad on legal continuity and reliability).
Political debates can be confusing when each party is using different meanings of the word “ought” (or similar word, like “should” or “must” or “needs to”). It is often disturbing, yet none the less true, that the legally required answer to a problem may differ or even conflict with what we consider the morally required answer.
Some have felt that it should be the obligation of the courts to alter the law so that the legally required answer aligns with the moral sensibilities of the community. This poses a problem in the face of US governmental structure because judges (all Federal and many state ones, at least) are not elected and as such lack the kind of connection to the voting democratic population that we associate with legislatures and executives (governors and presidents). The issue is this: In a democratic republic, should the unelected branch of government have veto power over the elected branch of government? This issue was brought to public attention last year in the 9th Circuit (mostly, California) when a ballot initiative passed popular vote but was struck down by a federal judge.
Some focus too much on the substance of the law in question, but that approach can’t provide categorical answers. If we think it is ok for the judiciary to strike down laws passed by the people, we must seriously question whether we are really true to the notion of democracy. If we think that the only check on the voice of the people should be the voice of the people, we might be concerned that if 51% of the people vote to kill/imprison/beat up the other 49% of the people just because they feel like it, there can be no kind of recourse or justice for that 49%.
This becomes the problem that is described in academic literature as the countermajoritarian difficulty vs. the tyranny of the majority. Should we allow the majority to be countered, or should we risk the majority abusing their power of the ballot? The Constitution establishes a framework for government, but it does not establish a meta-framework for itself.