Throughout American history federal courts have legitimated state-building by the political branches, setting new ground rules for what exercises of governmental power are permissible and impermissible. This is the best way to understand the role of the federal courts during the constitutional struggle over the New Deal and the Civil Rights revolution. Because the Affordable Care Act also involved a major change in the country's social contract, it was entirely predictable that the Supreme Court would be called upon to confirm the Act’s legitimacy and to ratify the changes to the social contract.
Judicial legitimation, however, is Janus-faced: The Court establishes what the government may do under the Constitution by simultaneously explaining what it may not do. In the Health Care Case, the Supreme Court upheld most of the Affordable Care Act, but in the process it also created new ground rules about federal power going forward. The precise scope of these rules will depend on the result of the next several presidential elections.