It seems that when the court overturns a law liberals like or upholds a law they oppose -- irrespective of whether it conforms to the Constitution -- they cry judicial activism.
Thus, Obama and liberals go berserk when the court, exercising its constitutional prerogative to pass on the constitutionality of laws, properly strikes down laws that are incompatible with our fundamental law -- when liberals support those laws. But that's not judicial activism; it's upholding the integrity of our structure of representative government.
Judicial activism is when courts uphold laws inconsistent with the Constitution or overturn laws that are consistent with it -- mostly to achieve a certain policy result. It's when courts act as super-legislatures, making up their own laws or substituting their political judgment for that of the democratically elected legislative branch in cases in which neither statutory nor constitutional interpretation warrants it.
Judicial activism is objectionable because it strikes at the very foundation of our government, which is not a "democracy" as Obama said, but a constitutional republic. If the court upholds or rejects laws based on nothing but its own political preferences, we have a government not of laws, but of nine robed men.
If the Supreme Court were to overturn Obamacare, it would not be engaging in judicial activism; it would be reining in a renegade president and Congress from their lawless power grab and reinforcing the integrity of the Constitution -- and thus our very republican form of government and its attendant liberties.
If the court were to uphold Obamacare, it would be thrusting another long knife in our ailing Constitution and, once again, violating the Constitution's scheme of limited government, which grants expressly enumerated powers to the legislative branch -- which do not include, even when coupled with the necessary and proper clause, the right to force people to purchase health insurance.
The irony is that ordinarily, liberals don't have any problem with true judicial activism; they've long been saying that the Constitution is a living and breathing document and that the court must often rewrite it to keep it in step with our "enlightened" modernity.
If President Obama wants to prevent assaults on what he inaccurately calls our "democracy," he should refrain from efforts to intimidate the court.