The 3rd separate but equal branch of US govt has virtually unrestricted power. While the other two branches powers are relatively highly defined and limited in the constitution, the federal Judicial branch is only constitutionally restricted in what kinds of law (cases) they can pass judgement on. All the rest of the Judicial branches powers to affect the other two branches are based soley on precidents set by the court over the years. Precident's are however not required to be used by subsequent courts. Precidents are only used by court and judicial tradition handed down from English common law, which the U.S. has used by pure tradition, but which isn't defined or requried by the constitution.
Thus U.S.'s basis for the rule of law is thus in fact without any constitutional guarantee or assurance at all. The Supreme Court has the power (by precedent) to pass judgement on laws passed by the legislative branch --- part of the check and balance system ---- but there is in fact no defined limits or conditions on the court's means of passing such judgements... which means in fact that any Supreme Court can redefine congressional law as "unconstitutional" at any time and virtually for any reason supported by the courts' desired, and arbitrary interpretation of constitutional powers.
We see for example in the current court four' justices that would turn back the clock at every opportunity presented to them... virtually undoing anything they believe doesn't meet the most restrictive interpretation of the constitution's literal reading. Normally these four are joined (and led) by the current Chief Justice so that for all intents and purposes there is a majority of the current court that would overturn much of the last two centuries of court interpretations that supported the enumerated constitutional powers, and continuously extended the powers of the other branches by effectively reading the constitution to allow that which isn't specifically restricted.
However, because the Court has no constitutional power to enforce their interpretations, rather must rely on the other two branches to accept their interpretations and act to enforce them, they are always cognizant of the risk that either both or one of the other branches will chose not to enforce their interpretation. The risk is that if the other branches don't enforce the court's decisions, then the Judicial branch ceases to have any real authority in gov't at all... at most thus acting in as legal board of interpretations --- with normally two versions of interpretations being provided and which two interpretations often only differ by one vote.
If such were to occur... i.e. a court decision that either one or both of the other powers chose to not follow... then the rule of law ceases to exist... i.e. law thence being only that which one or the other of the two remaining branches decides applies. With that then each new congress or executive can re-apply their own interpretation at will... which would often result in differences of interpretations between congressional and executive branches... leading to questions of which branch has the "right"... or more importantly, which branch exercises the ability to enforce its own interpretation.... and this is most often (historically from all other such cases in other nations) the executive branch.
In other words the Supreme Court must practically render its verdicts such that both other branches of gov't are willing to accept the verdicts, since if either (or both) do not, the role of the Supreme Court in governance becomes literally mute and leaves the path wide open for a complete break-down of the rule of law ... or better stated, the elevation of rule of laws created by the most economically powerful.
The court can, at any time it finds it to be beneficial to the majority interests of the justices opinions, modify constitutional interpretations of all past court opinions to literally overturn any of those rulings it decides were not in keeping with their own interpretation of the constitutional assurances and limits of power. It would only have to side-step the tradition (but no law or constitutional constraint) of using prior precedent to do so.
This can work both ways --- restrictive "Constitution in Exile" form or a full-out progressive interpretation, depending only on the then current inclination (majority) of the other branches of gov't then in power (to preserve the Court's power as a separate/equal branch of gov't and hence maintain rule of law because the other branches would therefore accept and enforce their interpretation). That it hasn't occurred yet doesn't mean it can't or won't occur and as we've seen in most if not all opinions by the conservative justices on the court, given the opportunity there's no reason why it wouldn't occur as the ideological bent of the conservatives on the court appear to reduce prior legal precedent to issues of selective definition of terms.
It is noteworthy that Justice Roberts chose to use prior precedent in upholding the health care mandate ---- in this he used prior precedent that required the court seek to find reason why a law should be found to be constitutionally supported rather than not. That he chose to use tax power of congress as the reason over the commerce clause is telling however. In using tax powers rather than the commerce clause to find reason to uphold the individual mandate wasn't without cost to the progressive view of the constitution... since the commerce clause is among the most progressive constitutional powers enumerated in the constitution and is without any enumerated limits. In short, Roberts chose to restrict gov't by specifically opining that the commerce clause only applies to existing commercial transactions.... thus specifically not being able to be applied to interstate transactions which may not be desired but which are necessarily required to regulate that commerce. In other words he specifically amended the constitutional power of congress to pass laws to regulate commerce among the states such that congress may not mandate business transactions to enforce the congressional laws based on the commerce clause.
At the same time, as Ginsberg's opinion elaborated, most of Roberts' opinion negating the power of the commerce clause to uphold the mandate were arbitrary and ignoring both prior precedent, re-interpreting or restricting prior court opinion after the fact, and using the conservative ideology to limit and redefine the constitutionally unlimited power of congress to regulate interstate commerce. If there were ever a case of judicial activism, Roberts opinion on the limits of the commerce clause takes the cake. Roberts' unilaterally rewrote the constitution's power of congress to regulate interstate commerce providing a limit where none is constitutionally provided. That no limits on regulating interstate commerce were enumerated in the constitution only reinforces the intent of the constitution to insure congress had the means to solve commerce between the states by whatever means it chose to use (subject only to being agreed by the majority of both houses and the executive... hence of and by the people in a representative form of gov't).
Objectively taken, the individual mandate is within the constitutional power of congress by 1) the unlimited power of congress enumerated by the commerce clause, 2) the enumerated power to tax, and 3) all prior precedent of Supreme Court interpretations of the commerce clause powers of congress. That Roberts' chose to accept only one of the three objective powers under the constitution and court precedent which uphold's the individual mandate, and reject the other two as having merit is not just difficult to understand from an objective point of view, but appears to be by specific intent to restrict the commerce clause's power.
I would guess that of the enumerated powers of congress the commerce clause's unrestricted power is the most objected to by the conservative ideology since it has the greatest potential and ultimate means of directly adversely affecting the capital owners association more than any other constitutionally provided power. Using that power, for example, a progressive political govt (congress & executive) could enact a single payor national health care system, virtually eliminating (or restricting to the level of insignificant) the private insurance and medical industry's role in health care in the commercial sense. It could also be used to nationalize all banks and financial instituions (since all banks, whether state or federally chartered) allow transactions using their checks, and other instruments (mortgages, loans, deposits, investments) beyond the state boundaries in which the bank has it's headquarters or branch(es).
In short, the commerce clause allows almost any federal restriction or activities of commerce of any significant national nature to become controlled by gov't and removed from significant control by private enterprise --- the only condition being that a majority of both houses of congress and the executive branch are in favor. If the laissez-faire, libertarian, ultra-right wing ideologies have anything to fear in the continuation, maintenance, and growth of their control of economic power in the U.S. then the constitutionally enumerated commerce clause is the ultimate vehicle for that fear to become manifest.
That the Supreme Court can control the powers of either of the other branches by their interpretation of the constitution based on their ideologies over prior precedent and legal objective, rational thought provides it with the literally unrestricted constitutional power over the other branches. They need but wait for the right time and confluence of conditions to exercise this power. If there were a solid six justices in favor of the Constitution in Exile, then it only need wait for the majority of both houses of congress and the executive branch to harbor the same view before exercising its unrestricted power to revise the past 200 years of constitutional law and interpretations to set back the clock to something akin or close to the continental congress's view of the federal gov't.