In most circumstances, the Constitution does not oblige the courts to give any deference to the legal judgments made by legislative or executive actors in the performance of their legislative or executive functions. The enforcement powers of the Reconstruction amendments are like most congressional powers in that respect. Those amendments give Congress substantial law-making power, and the courts may be obliged or permitted to defer to Congress’ judgment about the suitability of its chosen means to the Constitution’s ends. The ends Congress may pursue, however, are specified by the Constitution. For the Reconstruction amendments, those ends are found in the amendments’ substantive provisions. Congress has no special power to resolve unclarity in the Constitution’s formulation of those substantive rules, such as the Privileges or Immunities Clause. Because Congress has no such power, the courts can resolve such issues for themselves even if they do not have the power claimed for them in Cooper v. Aaron, the power to bind other government actors to their opinions and not just their judgments.
Judicial review of statutes, and the independent judicial determination of legal questions it entails, need not rest on the assumption that the courts have a special role of legal and constitutional interpretation, and that their interpretations conclusively bind other government actors. John Marshall did not rest his argument in Marbury v. Madison, on that premise, and it is highly unlikely that he subscribed to it. Rather, Marshall argued that the courts had to perform their own task of deciding cases independently of the legislature. Whatever Congress may have thought about the constitutionality of its statute, the court had an obligation to identify the law, and to interpret the Constitution, for itself.
Marshall’s argument rests on an assumption about the difference between judicial and legislative power that is not expressed but that is sound. The essence of judicial power is the final resolution of concrete legal disputes. Final resolution means that a judgment stands even if the legal conclusion on which it rests is erroneous. Congress has no such power with respect to legal questions, but not because the courts have a special responsibility to interpret the Constitution. Rather, Congress cannot bind others in that fashion because legislative power is not judicial power. Congress’ policy judgments are binding insofar as they are reflected in statutes, but nothing about the power to legislate entails that legal conclusions reached in the process of legislating are authoritative.
Some of the powers the Constitution gives Congress are formulated so that their content depends on the meaning of some other part of the Constitution. Most prominent as an historical matter is the Necessary and Proper Clause, which authorizes Congress to carry into execution its own powers and those of other parts of the national government. In order to know which laws carry into execution the postal power, for example, it is necessary to know about the postal power. If the postal power includes the establishment of telegraph offices, then laws providing for the physical security of telegraph offices will be necessary and proper. Whether Congress may legislate under the Necessary and Proper Clause also depends on the suitability of Congress’ chosen means to the Constitution’s given end. In order to assess whether Congress has properly exercised its power to implement other powers, it is thus necessary to make both legal judgments about those other powers and practical judgments about the likelihood that some means will achieve its end.
Courts routinely defer to congressional judgments about such practical issues. That deference, whether justified or not under the Constitution, does make functional sense. Legislators are chosen for their knowledge of the likely consequences of their policy choices, and their ability to make sound decisions in tailoring those choices to their goals. Whether the federal government’s financing requirements called for a private bank able to operate in every state was best decided by those who knew the most about the federal government’s fiscal operations. Whether the power to provide a navy includes the power to establish a federal merchant marine, by contrast, is one of legal interpretation. Nothing about the function of legislators suggests that they can answer that question better than a court can. So when courts go about their own function of deciding cases according to law, they have reason to defer to congressional means-end conclusions but not congressional legal conclusions.
The enforcement powers contained in constitutional amendments, in particular the three reconstruction amendments, have the same structure. Congress is given a power to pursue a goal: the power to enforce the amendments’ substantive provisions. Whether a ban on literacy tests will inhibit literacy tests that are used to discriminate by race is a practical question, like that of the usefulness of a bank in conducting federal financial transactions. Whether discrimination against Latinos constitutes discrimination on the basis of race, color, or previous condition of servitude, by contrast, is a legal question. Courts have no reason to defer to Congress about it.
Many of those who participated in adopting the reconstruction amendments said that the amendments would substantially increase congressional power. They were right, and were right even if the amendments entail no special interpretive authority for the legislature. Under Section 2 of the Fifteenth Amendment, for example, Congress can take the extreme step of entrusting the conduct of state elections to federal election officials, if it justifiably concludes that state officials will discriminate on the basis of race in ways that otherwise cannot be prevented or undone. Giving Congress power to make the amendments effective was a major increase in federal authority. From the many statements that the amendments increased Congress’ power one therefore cannot infer that they granted interpretive authority, because the new necessary-and-proper powers were themselves substantial additions to Congress’ enumerated authority.
Moreover, the drafting history of the 13th, 14th, and 15th amendments is hard to reconcile with the claim that they give Congress expanded interpretive authority. The 13th amendment’s Section 2 gives Congress power to enforce Section 1, which bans slavery. Claiming to act under Section 2, Congress enacted the Civil Rights Act of 1866, which went beyond a ban on slavery and invalidated many racially discriminatory state laws. Even some Republicans had doubts about Congress’ power to go so far under Section 2 of the 13th amendment, for example because the legislation operated in states that had never had slavery but did have race discrimination. Those doubts were one reason for including Section 1 in the 14th amendment. In order to resolve them, Congress did not propose an amendment that would simply increase substantive congressional power; indeed, the House of Representatives rejected such a proposal. Nor did Congress propose an amendment that provided for congressional interpretive authority. Rather, Congress proposed an amendment with a different substantive provision and the same enforcement authority as found in the 13th. When the 15th amendment was proposed, after disputes about the 14th’s meaning had already begun, it too followed that pattern. None of the Reconstruction amendments mentions congressional power conclusively to interpret the Constitution in enforcing them.
Insofar as interpretation of those provisions looks to the goals and policy views of the people who adopted them, it is important to bear in mind that constitutional amendments require super-majority coalitions. With respect to congressional proposal of any one of the reconstruction amendments, the important question in this respect is not what Republican leaders thought or what most Republicans thought. The important question is what Senators and Representatives at the two-thirds margin thought, and the members of Congress who occupied that position were hardly the average Republican. Like any American political party, the Republicans were a coalition. That one included many former Democrats who opposed slavery but believed in decentralization. Whether many of them wanted to give Congress both new substantive power and the ability conclusively to determine the scope of that power by making binding interpretations of the amendments is highly doubtful.
Neither the Constitution’s separation of legislative and judicial power in general, nor the text, structure, and history of the reconstruction amendments in particular, supports the conclusion that the courts should defer to Congress regarding the amendments’ meaning. In giving Congress no such deference, the courts need not claim that they alone interpret the Constitution, or that their interpretations bind other branches. They need only claim that they must decide for themselves the legal issues that come before them in cases within their jurisdiction.
 Judicial power and legislative power are dissimilar with respect to their binding force, and hence in some ways the binding force of judicial interpretations differs from that of legislative interpretations. To reason from the supposed “coequal interpretive authority” of the different branches is to reason from a premise not contained in the Constitution. Whether Congress has any interpretive authority, and if so whether it is in any sense coequal with that of the courts, is a question in this context. To assume that it does without explaining why and what that statement means is to assume the conclusion.
 The means-end connection between federal fiscal operations and a federally-chartered private bank was a central question when the Supreme Court considered Congress’ authority to charter the Second Bank of the United States in M’Culloch v. Maryland.
 In my view, Cooper was wrong on that point. As I explain, rejecting that claim of judicial supremacy does not undermine the courts’ claim independently to interpret the Constitution.