A Constitution that divides power among three branches and between the federal government and the states needs an umpire. Politicians, responding either to their own interest in expanding their authority or to public passions, will frequently overstep constitutional boundaries.

　　Through judicial review, the Supreme Court therefore serves as a neutral arbiter charged with maintaining the Constitution’s boundaries. But the Court itself is an institution that must respect its own boundaries. Thus, in every constitutional case, the preliminary question is whether the Court can reach and resolve the constitutional issue in a manner consistent with the proper limits on its own power. This term, in two of its most notable cases, Trump v. Barbara and Trump v. Cook, the Court transgressed those constraints. In both cases, it could have decided against the president but on narrower grounds that would have respected the bounds of its institutional role.

　　The problem in both cases is that the Court decided constitutional questions, although doing so was unnecessary.

　　The Duty to Avoid

　　The Court’s duty of constitutional avoidance has roots in the Constitutions original meaning, the Court’s history and tradition, and prudential and institutional concerns.

　　The original meaning of the judicial power reflected the notion that judicial review was, in Justice James Iredell’s words, “a delicate and awful” power, to be used only when necessary. Philip Hamburger has shown that judicial review emerged only when it was impossible to reconcile the Crowns action with the law, leaving the judiciary no choice but to refuse to follow the monarchs conscience. The early Supreme Court also stated that it was not proper to invalidate legislation in doubtful cases.

　　The Court later translated this general understanding of judicial power into explicit doctrine in nineteenth-century cases such as Liverpool, New York Philadelphia Steamship Co. v. Commissioners of Emigration (1885). There, the Court made clear that it should not anticipate constitutional questions before necessity requires, and that it should not formulate a constitutional rule broader than the facts demand. Justice Louis Brandeis relied on such cases when he offered the canonical formulation in Ashwander v. Tennessee Valley Authority (1936). He made it clear that the Court should not decide a constitutional question if another ground will dispose of the case.

　　The Court has reiterated this position often in modern times. In Alabama State Federation of Labor v. McAdory (1945), the Court refused to decide broad constitutional attacks on a state labor statute because the record and the state-law construction of the statute were uncertain. The Court said it was its practice not to decide abstract or hypothetical questions, not to decide constitutional questions in advance of necessity, and not to formulate broader constitutional rules than the facts require. In Rescue Army v. Municipal Court (1947), the Court described a “policy of strict necessity” in constitutional adjudication that began in Hayburn’s Case and continued through justiciability and advisory-opinion doctrines. It said that this policy was not merely procedural but “one of substance” because it was key to the proper institutional role of the Court.

　　Thus, for a Court that supplements originalist decision-making with history and tradition, the rule against deciding constitutional questions unnecessarily has unimpeachable support. Beyond original meaning, and history and tradition, constitutional avoidance is also supported by prudential considerations of the kind Alexander Bickel celebrated as the “passive virtues” of the Supreme Court. Bickel’s point was that the Supreme Court’s countermajoritarian mission of enforcing the Constitution against the political branches was democratically delicate and made the Court vulnerable. His solution was not that the courts should abandon constitutional judicial review, but that they should use it sparingly, husbanding their political capital. Thus, they should certainly not make constitutional decisions unless strictly necessary.

　　Seeking Out Constitutional Questions

　　Despite this longstanding practice, the Court reached out this term to decide constitutional issues in two of its most important cases, setting aside original structure, precedent, and prudence. In Trump v. Barbara, the majority passed up the opportunity to decide the case based on the Immigration and Nationality Acts citizenship criterion and instead interpreted the Fourteenth Amendment to favor birthright citizenship. It is true that the words in the Act and the Constitution were the same. But the context of the Act made the meaning of its words much more obvious.

　　Umpires’ names are generally lost to history, but the names of Supreme Court justices are not. They therefore face an ever-present temptation to favor legacy over duty.

　　In his concurrence, Justice Brett Kavanaugh supported a statutory disposition. Before the Act was passed, he noted, the Court had decided United States v. Wong Kim Ark, holding that the Fourteenth Amendment was “declaratory” of the “fundamental rule of citizenship by birth” that prevailed at common law. That rule included as citizens all those born “subject to the jurisdiction” of this country, in the language of the Amendment, and exempted only the children of ambassadors and those born into Indian tribes, who were not subject to the jurisdiction. All others were citizens at birth, whether born to permanent residents or temporary visitors. It is well settled that Congress is deemed to legislate against the background of Supreme Court precedent. If Congress had aimed to take issue with the Wong Kim Ark understanding, it had every opportunity to make that clear in the statute, but did not do so. Thus, the words in the Act are properly given the meaning they had been given by the Supreme Court, whatever the original meaning of the Fourteenth Amendment.

　　Moreover, Kavanaugh observed that birthright citizenship, with these exceptions, had been the consistent interpretation of the executive branch before the Immigration and Nationality Act and was also the contemporaneous interpretation of that Act. Neither the majority nor any of the dissents disputed his analysis. It is hard to know what they could have said. No one challenged Congress’s authority to confer citizenship beyond what the Fourteenth Amendment requires. Birthright citizenship is a constitutional floor, not a ceiling; the Fourteenth Amendment question did not need to be resolved

　　In some ways, Trump v. Cook is even more problematic. There, unlike in Trump v. Slaughter, the administration did not challenge the constitutionality of the for-cause language of the Federal Reserve Act, nor did it argue that the Federal Reserve could not be deemed an independent agency. Yet again, however, the Court reached out and declared that insulating the Federal Reserve from presidential at-will removal was constitutional. It did so on the theory that Congress had authorized the First and Second Banks of the United States in the early Republic. But restrictions on the removal of the officers of those earlier central banks were never contested, and it is far from clear that those banks exercised executive power comparable to that of the modern Federal Reserve, with its substantial regulatory responsibilities.

　　Justice Amy Coney Barrett here played the role that Justice Kavanaugh did in Barbara, noting in her concurrence that this constitutional issue was unnecessary to decide. The Court’s majority defended its choice to wade into the constitutional waters by noting that Justice Thomas had raised the issue in his dissent. But that was no answer: the government had conceded the point, and the Court’s own party-presentation principle required it to honor the concession.

　　The Court’s Political Judgment

　　Although the Court had no legal basis for addressing these constitutional issues, it may have believed it was doing the nation a favor by deciding them. Richard Re has observed that some of the Court’s language suggests that putting the issue to bed would create important stability, presumably for the markets. But the necessary stability had already been provided by the government’s concession. Donald Trump is both the most norm-breaking president since Andrew Jackson and the most virulent critic of the Federal Reserve in modern times. Yet even his administration did not challenge the Fed’s independence, precisely because the instability it would cause would undermine its own standing.

　　Thus, the Supreme Court’s imprimatur was unnecessary even to accomplish its proclaimed objective. It also came at a cost to the Court’s own standing: as Barrett pointed out, its reasoning was inconsistent with Trump v. Slaughter, decided during the same term, which held that the president must possess at-will removal authority over agencies exercising executive power. Likewise, on immigration, the Court may also have thought that resting its Barbara decision on the Constitution contributed to stability in immigration policy by taking the issue of birthright citizenship off the political agenda. But that is not obviously so either. There are many issues in immigration policy beyond birthright citizenship, and leaving the question to the political branches might have introduced another dimension of bargaining within the broader policy space. Conservatives, for instance, might have conceded birthright citizenship in exchange for stricter border controls and reduced asylum opportunities. Justices are poorly positioned to decide what makes for stable politics.

　　And while I think the majority was likely right on the constitutional issue, there is ongoing, vibrant debate in originalist scholarship on the question. Postponing the constitutional question may well have elicited more useful information, thereby making the result more certain.

　　Ed Whelan has suggested that Chief Justice John Roberts may have decided the case on constitutional grounds because the liberal justices would have insisted on that basis of decision. Perhaps they would have, but they could not have formed a majority without the chief justice and Justice Barrett. Even if there were no majority rationale, the chief would have had the opportunity to school them in important constitutional and conservative virtues. And how could the liberal justices have avoided concurring in his statutory result? It followed a fortiori from the constitutional one.

　　Sadly, justices—perhaps most of all chief justices—have trouble resisting the urge to go big in the biggest cases. Preserving birthright citizenship as a constitutional rule and securing the independence of the Federal Reserve will likely appear in the opening paragraphs of any retrospective on the chief justice and the Roberts Court. Yet at his confirmation hearing, John Roberts famously said that “no one ever went to a baseball game to see the umpire.” But umpires’ names are generally lost to history, but the names of Supreme Court justices are not. They therefore face an ever-present temptation to favor legacy over duty—not necessarily in their votes on the bottom line, but in writing opinions broader than the case requires. The duty of restraint may be less obvious than the duty to reach the right result, but it is no less compelling. A Court charged with maintaining the Constitution’s boundaries must respect its own.