Interesting piece by Indiana U's Gerard Magliocca in the Wash Post about what it takes for transformative laws to become fully accepted as "settled." A snippet:
Once both parties agree that something is untouchable, however, only a truly extraordinary effort by citizens can bring about change. In this sense, the parties serve as formidable guardians for the rule of law.
The Affordable Care Act is not settled law because the public remains deeply divided over it: More than half of Americans are opposed. But even more critically, congressional Republicans have withheld their stamp of approval. Many Republican lawmakers refuse even to call it a law; they keep referring to it as a "bill."
Republicans offer several explanations for their rejection of the act's validity. Most often, they note that the law was passed entirely with Democratic votes. This is in contrast to other major legislation, including the Civil Rights Act of 1964, which was enacted with overwhelming bipartisan support and thus became settled much more quickly.
Republicans also cite the unusual procedures used to pass the health-care act — most notably, the budget reconciliation process that avoided a filibuster while moving the final legislation through the Senate. This tactic left many Senate Republicans feeling cheated.
Interesting to think of other examples of how/when things become settled or not. For instance, it took about 25 years for Social Security to become "settled" in the way that Magliocca means. And it's also interesting and important to think about how some things—such as the military draft, say—become unsettled.
Then there's the whole question of just signing up for the goddamn thing.