The delegates to the Constitutional Convention declared, by resolution, that Congress should possess power to legislate “in all Cases for the general Interests of the Union, and also in those Cases to which the States are separately incompetent, or in which the Harmony of the United States may be interrupted by the Exercise of individual Legislation.” It was left to the Committee of Detail—a distinguished body consisting of four prominent lawyers (Oliver Ellsworth, Edmund Randolph, John Rutledge (chair), and James Wilson) and a prominent businessman (Nathaniel Gorham)— to translate that resolution into concrete form. At the Constitutional Convention, the Commit-tee of Detail took the Convention’s resolutions on national legislative authority and particularized them into a series of enumerated congressional powers. This formalized the principle of enumerated powers, under which federal law can govern only as to matters within the terms of some power-granting clause of the Constitution. By including the Necessary and Proper Clause at the conclusion of Article I, Section 8, the Framers set the criteria for laws that, even if they are not within the terms of other grants, serve to make other federal powers effective.

Although modern scholars often express bafflement at the Necessary and Proper Clause, the meaning and purpose of the clause would actually have been clear to an eighteenth-century citizen. The enumeration of congressional powers in Article I, Section 8 is similar to the enumeration of powers that one would find in an eighteenth-century private agency instrument or corporate charter. That is not surprising, as the Founders viewed the Constitution as, in the words of James Iredell, “a great power of attorney,” in which the principals (“We the People”) grant power to official agents (the government). Eighteenth-century agency law understood that grants of power to agents generally carried implied powers in their wake: the enumerated, or principal, granted powers were presumptively accompanied by implied, or incidental, powers that were needed to effectuate the principal powers. As William Blackstone wrote, “[a] subject’s grant shall be construed to include many things, besides what are expressed, if necessary for the operation of the grant.” Agency instruments accordingly often referred to “necessary,” “proper,” or (most restrictively) “necessary and proper” incidental powers of agents. A Committee of Detail composed of lawyers and a businessman would have written, and a public accustomed to serving as or employing agents in a wide range of everyday affairs would have recognized, the Necessary and Proper Clause as a provision clarifying the scope of incidental powers accompanying the grants of enumerated (or principal) congressional powers.

So understood, the Framers crafted the Necessary and Proper Clause to serve three great purposes. The first was to facilitate organization of the government, such as empowering Congress to organize the judicial department and to create executive offices. The second was to help effectuate the other enumerated powers of Congress. The third, and most general, was to define the limits of these implied or incidental powers.

As to the first purpose, the Constitution could not prescribe all points of government organization, so Detail Committee member Edmund Randolph proposed empowering Congress to “organize the government.” James Wilson proposed the “necessary and proper” clause as a substitute, authorizing laws “for carrying into Execution” the “other” federal powers. The committee, and then the Convention, approved. The organizational function of this clause was recognized from the outset. Among Congress’s first acts were establishing executive departments and staffs, determining the number of Justices of the Supreme Court, and allocating the judicial power among federal courts. The Supreme Court has acknowledged the Necessary and Proper Clause as the source of Congress’s power to legislate about judicial process and procedure.

As to the second and more significant purpose, the clause also supports laws for carrying into execution “the foregoing Powers,” that is, those specified for the legislature itself in Article I, Section 8. It thus enhances the other powers given to Congress. During the ratification debates, opponents dubbed it the “sweeping clause” and the “general clause,” arguing that it subverted the principle of enumerated powers by giving sweeping general legislative competence to Congress. The Anti-Federalist Brutus, for example, said it “leaves the national legislature at liberty, to do every thing, which in their judgment is best.” Defenders of the Constitution strongly disagreed. At Pennsylvania’s ratification convention, James Wilson, the author of the clause, explained that the words “necessary and proper” are “limited and defined by the following, ‘for carrying into execution the foregoing powers.’ It is saying no more than that the powers we have already particularly given, shall be effectually carried into execution.” It authorizes what is “necessary to render effectual the particular powers that are granted.” Congress thus can make laws about something otherwise outside the enumerated powers, insofar as those laws are “necessary and proper” to effectuate federal policy for something within an enumerated power.

The third purpose has the broadest implications for constitutional law. The Articles of Confederation expressly forbade any inference of incidental powers by specifying that “[e]ach state retains . . . every power, jurisdiction, and right, which is not by this Confederation expressly delegated to the United States, in Congress assembled” (emphasis added). The Constitution contains no such clause, and it is therefore appropriate to find some measure of implied congressional powers. Had the Constitution been silent about implied powers, the ordinary back-ground rules of agency law would have mandated inferring some measure of such powers to effectuate the enumerated powers, but would have left uncertainty about how broadly or narrowly to construe the implied powers. By selecting a relatively restrictive phrase—“necessary and proper,” in the conjunctive—to describe the range of implied congressional powers, the Constitution eliminated that uncertainty by limiting implied powers to those that bear a close relationship to the principal powers.

Accordingly, every law enacted under the Necessary and Proper Clause must meet four requirements: (1) it must be incidental to a principal power; (2) it must be “for carrying into Execution” a principal power; (3) it must be “necessary” for that purpose; and (4) it must be “proper” for that purpose. And, because the clause provides that all such laws “shall be” necessary and proper for executing federal powers, rather than prescribing that such laws “shall be deemed by Congress” to be necessary and proper, these inquiries are all objective, contrary to Brutus’s suggestion of unreviewable congressional discretion.

In McCulloch v. Maryland (1819), Chief Justice John Marshall confirmed the original understanding of the clause. He noted that other grants of power by themselves “according to the dictates of reason” would “imply” a “means of execution.” He went on, however, to declare that the Constitution “has not left the right of Congress to employ the necessary means for the execution of the powers conferred on the Government to general reasoning.” For the Chief Justice, the Necessary and Proper Clause makes express a power that otherwise would only have been implied and thus might have been subject to cavil. By implanting the clause among the powers of Congress, the Framers confirmed that Congress may act to make the constitutional plan effective. In his parsing of the words of the clause, he concluded that the Necessary and Proper Clause authorizes laws enacted as means “really calculated to effect any of the objects intrusted to the government.” Arguments for laws that lack this crucial means-to-end characteristic find no support in Marshall’s opinion or in the Necessary and Proper Clause.

While modern case law does not fully reflect the original meaning of the Necessary and Proper Clause, it has moved significantly towards conformance with original meaning in recent years, at least with respect to several of the clause’s requirements. Most notably, the modern Supreme Court has recognized, after a long period of neglect, the requirement that laws under the Necessary and Proper Clause be incidental to a principal power, as Marshall emphasized in McCulloch. The McCulloch case concerned in large measure whether the Necessary and Proper Clause authorized Congress to incorporate a national bank, given that neither the power to create a corporation nor the power to create a bank is among the principal (enumerated) powers of Congress. The Chief Justice devoted the bulk of his opinion to explaining why the power to incorporate a bank was incidental, that is, not as great as a principal power. He said that incorporation was “not, like the power of making war, or levying taxes, or of regulating commerce, a great substantive and independent power, which cannot be implied as incidental to other powers,” but rather “must be considered as a means not less usual, not of higher dignity.” If a power is not incidental—if it is of the same “dignity” or (as founding-era agency lawyers would say) as “worthy” as the principal enumerated powers—then it cannot be implied under the Necessary and Proper Clause, no matter how convenient, useful, or even indispensable it might be to effectuation of a principal power. This basic idea played a key role nearly two centuries later in Chief Justice John Roberts’ decisive opinion for the Court in National Federation of Independent Business v. Sebelius (2012), in which the Court upheld the Patient Protection and Affordable Care Act (PPACA) provision known as the “individual mandate” to purchase government-approved health insurance under the taxing power but found the mandate unsupportable by either the Commerce Clause or the Necessary and Proper Clause. In explaining why the mandate was not authorized by the Necessary and Proper Clause, Chief Justice Roberts wrote, extensively quoting McCulloch, that the clause “vests Congress with authority to enact provisions ‘incidental to the [enumerated] power’. . . . Although the Clause gives Congress authority to ‘legislate on that vast mass of incidental powers which must be involved in the constitution,’ it does not license the exercise of any ‘great substantive and independent power[s]’ beyond those specifically enumerated.” He concluded that a governmental power to force people to buy a product could not be “ ‘incidental’ to the exercise of the commerce power. . . . Rather, such a conception of the Necessary and Proper Clause would work a substantial expansion of federal authority.” Accordingly, it is now clear that any power claimed by Congress under the Necessary and Proper Clause must be incidental—meaning that it must not be the sort of power that an ordinary reader would assume must be enumerated as a principal power in order to exist.

In addition to being incidental to a principal power, any law enacted under the Necessary and Proper Clause must be “for carrying into Execution” some other federal power. The Necessary and Proper Clause allows Congress to decide whether, when, and how to legislate “for carrying into Execution” the powers of another branch; but it respects and even reinforces the principle of separation of powers. Unlike Randolph’s authorization to “organize the government”—which the Committee of Detail replaced with Wilson’s more exacting phrase—“laws . . . for carrying into Execution” the powers reposed in another branch—can only mean laws to help effectuate the discretion of that other branch, not laws to control or limit that discretion. It gives Congress no power to instruct or impede another branch in the performance of that branch’s constitutional role. For example, Congress could not, under the guise of this clause, dictate to courts how to decide cases, United States v. Klein (1871), or tell the President whom to prosecute. Of course, when the clause is invoked to effectuate ends within Congress’s own powers, it compounds Congress’s discretion: not only the selection of means, but also the selection of policy ends, rests in Congress’s own discretion.

Incidental laws that carry into execution federal powers must also be “necessary” for that purpose. The requirement of necessity entails some degree of causal connection between the implementing law and the implemented power. The degree of that required causal connection between the means chosen and the particular “end” sought, i.e., the specific enumerated power, has been a contentious issue for more than two centuries. Thomas Jefferson, and the State of Maryland in McCulloch, famously argued that a “necessary” law must be indispensable to the achievement of a permissible governmental end. Alexander Hamilton equally famously argued that necessity in this context meant merely that a law “might be conceived to be conducive” to a permissible end. And somewhat less famously, but no less importantly, James Madison trod a middle ground, describing necessity as requiring “a definite connection between means and ends” in which the executory law and the executed power are linked “by some obvious and precise affinity.”

In McCulloch, Chief Justice Marshall, writing for the Court, upheld the Second Bank of the United States, utilizing the very rationale that Secretary Hamilton, and James Wilson before him, had employed. Marshall rejected Jefferson’s view that the clause limits Congress to “those means without which the grant of power would be nugatory.” That would have precluded Congress from deliberating alternatives, and the Court read the clause instead as vesting “discretion, with respect to the means by which the powers it confers are to be carried into execution.” McCulloch countenanced “any means calculated to produce the end,” giving Congress “the capacity to avail itself of experience, to exercise its reason, and to accommodate its legislation to circumstances.” According to McCulloch, unless otherwise inconsistent “with the letter and spirit of the constitution,” any law that is “appropriate,” “plainly adapted to that end,” and “really calculated to effect any of the objects entrusted to the government” is valid under the Necessary and Proper Clause. For the judiciary “to inquire into the degree of its necessity,” Marshall said, “would be . . . to tread on legislative ground.”

So long as a law promotes an end within the scope of some enumerated power, extraneous objectives do not render it unconstitutional. Indeed, one means might be preferred over others precisely because it advances another objective as well. For example, besides helping Congress effectuate various enumerated powers, a bank could make private loans to augment business capital or to satisfy consumer wants; while these extraneous ends could provide no independent constitutional justification, Hamilton urged them as principal reasons why Congress should incorporate a bank. 

Record-keeping and reporting requirements regarding drug transactions, if apt as means to enforce federal taxes on those transactions, are no less valid because crafted for police ends that are not within any enumerated power. Extraneous objectives are constitutionally immaterial; but to invoke the Necessary and Proper Clause, a sufficient link to some enumerated-power end is constitutionally indispensable.

McCulloch remains the classic elucidation of this clause, but it has been elaborated in many other cases, such as in the proceedings concerning the Legal Tender Act of 1862. Congress, in an effort to stabilize commerce and support military efforts during the Civil War, determined that new paper currency must be accepted at face value as legal tender. The Supreme Court, in the Legal Tender Cases (1871), affirmed Congress’s discretion to choose among means it thought conducive to enumerated-power ends. The Court upheld Congress’s choice, even though better means might have been chosen, and though the legal tender clause proved to be of little help: “The degree of the necessity for any Congressional enactment, or the relative degree of its appropriateness, if it have any appropriateness, is for consideration in Congress, not here,” said the Court.

Modern cases have interpreted these precedents to require that laws under the Necessary and Proper Clause accomplish valid legislative ends “by rational means,” Sabri v. United States (2004), or by “a means that is rationally related to the implementation of a constitutionally enumerated power,” United States v. Comstock (2010). In Comstock, four Justices (Samuel Alito, Anthony Kennedy, Antonin Scalia, and Clarence Thomas) expressed—in three different opinions and three different forms—some measure of unease with this “rational basis” formulation of the required means-ends connection, though only Justice Thomas has specifically endorsed the Madisonian formulation as an alternative.

Finally, laws under the Necessary and Proper Clause must be “proper” for executing federal powers. It is textually clear—and five Justices in NFIB v. Sebelius have confirmed—that the requirement of propriety is separate from and in addition to the requirement of necessity. Given the agency-law origins of the Necessary and Proper Clause, it is evident that the term “proper” imports into the clause basic fiduciary principles, that is, the means must be true to the end of effectuating a principal power. As Chief Justice Marshall famously warned, “Should Congress, in the execution of its powers, adopt measures which are prohibited by the Constitution, or should Congress, under the pretext of executing its powers, pass laws for the accomplishment of objects not intrusted to the Government, it would become the painful duty of this tribunal, should a case requiring such a decision come before it, to say that such an act was not the law of the land.”

The modern Supreme Court has not elaborated upon this requirement of propriety in detail, but a majority of Justices of the Court have endorsed some version of it in recent years. Several late twentieth-century cases held that laws failed to be “proper” if they violated principles of federalism by compelling state officials to enforce federal law, Printz v. United States (1997), or by wrongly using Article I powers to abrogate state sovereign immunity, Alden v. Maine (1999). In NFIB v. Sebelius, four Justices clarified that “the scope of the Necessary and Proper Clause is exceeded not only when the congressional action directly violates the sovereignty of the States but also when it violates the background principle of enumerated (and hence limited) federal power,” and a fifth (Chief Justice Roberts) noted that laws are not “proper” when they “undermine the structure of government established by the Constitution” and specifically found that the individual mandate of the PPACA “is not a ‘proper’ means” for effectuating the statute’s insurance reforms.

On the other hand, the Court has decided a number of recent cases involving the Necessary and Proper Clause, most notably Sabri v. United States (2004) and United States v. Comstock (2010), without conducting a separate inquiry into whether the challenged law is “proper.” It remains to be seen how fully an analysis of propriety becomes integrated into modern doctrine.

The Necessary and Proper Clause, along with its in-built limitations, is the relevant source of congressional power in many contexts. For example, federal tax lien and collection laws; record-keeping, reporting, and filing requirements; and civil and criminal penalties for non-payment are not themselves exertions of Congress’s power to tax, but are laws “necessary and proper for carrying into Execution” the federal taxing power. That is why “provisions extraneous to any tax need” are not rendered valid simply by inclusion in a tax statute. United States v. Kahriger (1953); see also Linder v. United States (1925). Similarly, with regard to federal condemnation of property, “the really important question to be determined” is whether “it is necessary or appropriate to use the land in the execution of any of the powers granted to it by the constitution.” United States v. Gettysburg Electric Railway Co. (1896). Finally, some scholars believe that the Necessary and Proper Clause is the source of federal spending authority, though modern doctrine locates that power in the Article I, Section 1 Taxation Clause (while other scholars locate it in the Article IV, Section 3 (Territories and Property Clauses).

Perhaps the best-known use of the clause is to regulate matters that do not constitute commerce among the states (or with foreign nations or the Indian tribes) in order to effectuate exercises of Congress’s power under the Commerce Clause. The Necessary and Proper Clause’s enhancement of Congress’s power over commerce among the states had been judicially recognized decades before Congress began to exercise that power extensively. See Gilman v. Philadelphia (1866). Its means-to-end logic underlay the Supreme Court’s approval of anti-trust prosecutions for local monopolies when the government could prove a purpose to restrain interstate trade, Addyston Pipe & Steel v. United States (1899), but not when the government omitted to prove such a purpose, United States v. E.C. Knight Co. (1895). The same rationale sustained an amendment to the Safety Appliance Act, which prescribed safety equipment for railcars used only within a state, because the amendment increased safety for interstate cars and cargos on the same rails. Southern Railway v. United States (1911). Likewise, the Interstate Commerce Commission could authorize carriers to disregard state limits on rates for trips within a state, as a means to eliminate price discrimination against interstate commerce. Shreveport Rate Case (1914). Upholding the wage and hour provisions of the Fair Labor Standards Act on this ground in United States v. Darby (1941), the Court cited not only those older cases but also NLRB v. Jones & Laughlin Steel Corp. (1937) as illustrating the rationale of the Necessary and Proper Clause.

The Necessary and Proper Clause does not confer general authority over a matter simply because its regulation in some respects might serve an enumerated-power end; it only supports the particular regulations that have such an effect. For example, what mattered in Jones & Laughlin was not that steel manufacturing impacts interstate commerce, but rather that applying the particular National Labor Relations Act provisions prohibiting those factories’ unfair labor practices would promote Congress’s policy of uninterrupted interstate commerce in steel. Similarly, in Heart of Atlanta Motel v. United States (1964), Title II of the 1964 Civil Rights Act was held applicable, not because hotels affect interstate commerce, but because prohibiting racial discrimination by hotels promotes Congress’s interstate commerce policy of unimpeded travel.

Often the Supreme Court has not articulated the Necessary and Proper Clause basis of its so-called “affecting commerce doctrine,” but has instead written as though matters affecting commerce could be reached directly under the commerce power. This omission led to one of the most confused areas of all constitutional law. Justice Sandra Day O’Connor, however, did emphasize it: first in her dissent in Garcia v. San Antonio Metropolitan Transit Authority (1985), and then for the majority in New York v. United States (1992). Justice Scalia specifically articulated the role of the Necessary and Proper Clause in his concurring opinion in Gonzalez v. Raich (2005).