The difference may well be the result of the fact that a substantial minority of the public will tend to assume that any decision the Court makes is likely to be right unless they have very strong personal feelings on the subject.But as Somin admits, pubic opinion of itself "says very little about whether [a] ruling is right or wrong" and some Supreme Court opinions that, in retrospect, seem backward, even atrocious, were popular at the time they were issued. Let's recall also that some opinions that were broadly unpopular, or unpopular in the regions of the country most affected by the outcome, now enjoy broad public support and acceptance. Somin notes that First Amendment opinions on flag burning, although legally correct, are unpopular.
Nonetheless, this result undermines the notion that the ruling will be a boost to the Court’s legitimacy or that its public image would have suffered had it ruled the other way. It’s unlikely that the Court’s legitimacy improved much in the eyes of anyone but committed liberals and legal academics.
In other words, a snapshot of public opinion means next to nothing.
I personally believe that Roberts crafted this opinion to try to quiet a lot of sound and fury in a manner that, quite possibly, will end up signifying nothing. I am skeptical that any of the significant holdings of the court will pose a problem to future sessions of Congress. You can't modify a federal grant without allowing states to maintain the status quo because that would be too coercive? Okay - we'll explicitly end the old program and create a new one. You can't impose a mandate under the Commerce Clause? We'll rephrase, or make it a tax. The case as it stands will most likely signify a turning point toward or away from the dissenters' perspective on the limits of the Constitution, but Roberts otherwise seemed to be composing an outcome he expects history to largely forget. Legal scholars will take note if future cases build off of this decision, but beyond that there's not much to remember. Reversing the ACA? That would have been an opinion for the history books.
I do not believe that the Court should decide cases based on the perceived effects on its “legitimacy.” But for those who disagree, the individual mandate decision was not the great triumph that some imagine it to be.In a big picture sense, of course the Court shouldn't focus on its "legitimacy". It should focus on the law and Constitution. Nonetheless, it will inevitably be presented with difficult questions for which there is a genuine difference of opinion about constitutionality, and it's appropriate for the Supreme Court in those contexts to consider its role in our system of government - as one of three co-equal branches of government - and to act as a court, not a legislature.
That's something conservatives have argued for years - that "judicial activism" harms the court as an institution. While reiterating that "judicial activism" is often a subjective concept and, depending on how you define it, does not have to involve acting outside of the scope of the Constitution and can actually benefit society - Brown v. Board is widely regarded as an activist decision - there's a lot of merit to the argument that political victory should come at the ballot box and not the courthouse.
That argument seems considerably stronger when a court is asked to review legislative action, as opposed to inaction, and again stronger when the legislation at issue was a significant issue in that party's election campaign. When the best the Supreme Court can say on a difficult constitutional question is, "It's a coin toss," there's a certain, potentially corrosive arrogance to nonetheless rejecting the opinion of both the Executive and Legislature that a particular legislative act is constitutional.
I believe that Roberts is aware that this is his court and his legacy, and that his status as Chief Justice of "The Roberts Court" influences how he approaches cases. But to the extent that thoughts of a legacy influence a judge, its better that the effect be to inspire modesty than arrogance.