The most important influence on the Supreme Court is its conception of its own role. It is unseen only because it’s so familiar as to be unremarked.
A decision from the last term well illustrates alternative conceptions of the Supreme Court.
Justice Scalia describes the contrast.
On the one hand:
an assertion of judicial supremacy over the people’s Representatives in Congress and the Executive. It envisions a Supreme Court standing (or rather enthroned) at the apex of government, empowered to decide all constitutional questions, always and everywhere primary’ in its role.
On the other:
The judicial power as Americans have understood it (and their English ancestors before them) is the power to adjudicate, with conclusive effect, disputed government claims (civil or criminal) against private persons, and disputed claims by private persons against the government or other private persons. Sometimes (though not always) the parties before the court disagree not with regard to the facts of their case (or not only with regard to the facts) but with regard to the applicable law-in which event (and only in which event) it becomes the “province and duty of the judicial department to say what the law is.'” In other words, declaring the compatibility of state or federal laws with the Constitution is not only not the “primary role” of this Court, it is not a separate, free-standing role at all. We perform that role incidentally-by accident, as it were-when that is necessary to resolve the dispute before us. United States v. Windsor, 570 U.S. __ (Scalia, J. dissenting).
It’s not hard to see how this self-conception influences the Court’s approach to its work and its decisions. One need not assume any malign motives. Rather, it seems to follow that if the Court has adopted the role as the grownup in national debates, it must take on the contentious cases which cannot be trusted to the political branches whose motives, the narrative goes, are likely to be less exalted.
Not only are the political branches not capable of handling important issues, neither, increasingly, are the people of the United States.
Thus, when the Court reconsidered its 1973 rulings (Roe v. Wade and Doe v. Bolton) legally mandating abortion on demand in 1992, the plurality opinion characterized the Roe decision as an instance where “in the performance of its judicial duties” the Court had “resolve[d]” an “intensely divisive controversy.” The opinion said that its ruling involved “a dimension that the resolution of the normal case does not carry. It is the dimension present whenever the Court’s interpretation of the Constitution calls the contending sides of a national controversy to end their national division by accepting a common mandate rooted in the Constitution.” Planned Parenthood v. Casey, 505 U.S. 833 (1992). In plain English: “we’ve settled this, stop protesting.”
A corollary of the Court’s self-conception that leads it to believe it is and should be the arbiter of all significant social controversies, is a need to create rationales to decide these knotty questions. Since the text of the Constitution is almost always silent on such matters, the Court must cast about for extraconstitutional principles even if doing so risks elevation of the social attitudes of judges or the legal profession to the status of law. This is the impetus for the Court’s penchant for creating “tests” or “levels of scrutiny.” Thus, this passage from Casey: “At the heart of liberty is the right to define one’s own concept of existence, of meaning, of the universe, and of the mystery of human life.” Planned Parenthood v. Casey, 505 U.S. 833 (1992)
This is but once instance of the Court importing an extraconstitutional “rationalism” into its decisions. As Professor Robert Nagel notes: “the rationalist prefers knowledge that is susceptible of formulations in rules, principles, directions, maxims: comprehensively, in propositions.'” He explains that the Supreme Court “[i]n its drive to find ever more expansive values in the Constitution” embraces abstractions because “[i]f a value is sufficiently abstract it will necessarily seem to have broad relevance to human affairs, important or petty.” However, “[t]reating social choices as a series of intellectual problems is reassuring to many in the educated classes,  also tends to denigrate important values and to stunt moral and political discourse.” Thus, “to the extent that constitutional rationalism forces communities to explain their decisions in terms of relatively remote relationships between policies and objectives, absurd purposes are postulated and important values are unfairly trivialized.” Robert F. Nagel, “Rationalism in Constitutional Law” Constitutional Commentary vol. 4, page 9 (1987).
Integrity of the Law
Additionally, the Court’s own status becomes more important than other factors, even than the integrity of the law. Again from Casey:
The Court must take care to speak and act in ways that allow people to accept its decisions on the terms the Court claims for them, as grounded truly in principle, not as compromises with social and political pressures having, as such, no bearing on the principled choices that the Court is obliged to make. Thus, the Court’s legitimacy depends on making legally principled decisions under circumstances in which their principled character is sufficiently plausible to be accepted by the Nation.
The need for principled action to be perceived as such is implicated to some degree whenever this, or any other appellate court, overrules a prior case. Planned Parenthood v. Casey, 505 U.S. 833 (1992).
In other words, if we overrule a bad decision, people will think we’re making this stuff up and we can’t let that happen. Commentators openly talk of decisions being made only to protect the court from criticism.
Once the judicial process is cut off from the text and established precedent, the new Court-created rationale can even displace the text.
For instance, the Fifth Amendment allows takings of private property only for “public use.” In a 2005 case, the Court assessed the constitutionality of a city’s taking of property from one private owner only to give it to another, pursuant to the city’s economic development plan. The text of the Constitution should make this an easy case, but the Court interpreted “public use” to include the generalized (and hypothetical) public benefit the seizure would provide. Kelo City of New London, 545 U.S. 469 (2005).
This approach to the judicial role has wide implications.
It jeopardizes the very concept of a written constitution. As clear textual direction yields to Court-created doctrines, judicial preferences and concerns about judicial prestige, the Constitution itself appears no more than a launching pad for increasingly far-ranging flights of novelty. The very notion of a written Constitution requires that words matter. Judicial supremacy teaches “ordinary people the scary lesson that anything can be done with words.” Robert F. Nagel, “Playing Defense” 6 William & Mary Bill of Rights Journal 167, 185 (1997). It also teaches that personnel matters, perhaps more than any other factor.
Each Branch Its Own
In his 1780 constitution for Massachusetts, John Adams linked separate of powers with the rule of law, providing that the various branches of government should “never” exercise the powers of the other “to the end it may be a government of laws and not of men.” Massachusetts Constitution, article XXX. Our current situation looks too much like the latter.
It infantilizes the other branches of government. Remember when Congress approved the McCain-Feingold Act in 2002 to strictly regulate political speech, President George W. Bush signed the law despite “reservations about the constitutionality of the broad ban on issue advertising, which restrains the speech of a wide variety of groups on issues of public import in the months closest to an election.” Why not just veto, then? “I expect that the courts will resolve these legitimate legal questions as appropriate under the law.” Statement on Signing the Bipartisan Campaign Reform Act of 1992, March 27, 2002 .
Legislators, too, are often afraid of making decisions for fear of what the courts will do.
In a variation on the above, executive officials who fail to achieve their aims in the normal political process, such as with the Defense of Marriage Act or Proposition 8, can always accomplish their aim in the courts by failing to defend the law and allowing the court to deliver the death blow.
Ironically, laws that probably should not be struck down (because the Constitution does not speak to the issues) are and laws that ought to be (because they transgress an actual constitutional principle) are not.
What About Us?
Where does all this leave individual citizens?
Recognizing that the adage personnel is policy is basically an iron law when it comes to the Supreme Court, voters considering presidential and senatorial candidates should make the question of Supreme and lower court nominees a paramount consideration. Elected officials must be committed to ensuring that any individual nominated or confirmed to the courts is fully committed to restoring the Court to its Constitutional role rather than to a novel doctrine of judicial supremacy.
Judges, of course, are drawn from the legal profession (though why this is thought necessary is unclear). And, as Justice Alito has noted, there is a strain within the profession of “an arrogant legal culture that has lost all appreciation of its own limitations.” Thus, legal training and other education should be adjusted to refocus citizens and potential lawyers on the matters central to the Framers’ design-limitations on government authority and the structure of decision-making (including separation of powers within the national government and between that government and the states)-that ensure self-government through representation and away from novel impositions such as centralized power presided over by a national council of censors.
The constitutional structure highlights another potential limiting factor on the role of the courts; specifically, the primacy of states. States can play a crucial role in pushing back against unauthorized judicial policy-making. The Institute for Justice, for instance, explains that in just two years after the Kelo takings decision, “44 states  passed new laws aimed at curbing the abuse of eminent domain for private uses.” Castle Coalition, “50 State Report Card“. Since 1973, states have consistently worked to protect unborn life through incremental protections with great effect.
In dissenting from the same-sex marriage decision of the Court this last term, Justice Scalia warned that the only limiting factor on the Court’s decision of whether to force marriage redefinition on the states would be what the justices think they can get away with. That’s a sobering warning but it does give us somewhere to start.