Questions of the above kinds sometimes arise as questions of interpretation in the strict sense of the term, i.e., as questions of the meaning of a term or phrase which is so far ambiguous that it might be taken either to cover or not to cover a case apparently contemplated by the people when they enacted the Constitution. Sometimes they are rather questions to which we may apply the name of construction, i.e., the case that has arisen is one apparently not contemplated by the enacters of the Constitution, or one which, though possibly contemplated, has for brevity’s sake been omitted; but the Constitution has nevertheless to be applied to its solution. In the former case the enacting power has said something which bears, or is supposed to bear, on the matter, and the point to be determined is, What do the words mean? In the latter it has not directly referred to the matter, and the question is, Can anything be gathered from its language which covers the point that has arisen, which establishes a principle large enough to reach and include an unmentioned case, indicating what the enacting authority would have said had the matter been present to its mind, or had it thought fit to enter on an enumeration of specific instances?5 As the Constitution is not only a well-drafted instrument with few ambiguities but also a short instrument which speaks in very general terms, mere interpretation has been far less difficult than construction.6 It is through the latter chiefly that the Constitution has been, and still continues to be, developed and expanded. The nature of these expansions will appear from the nature of the federal government. It is a government of delegated and specified powers. The people have entrusted to it, not the plenitude of their own authority but certain enumerated functions, and its lawful action is limited to these functions. Hence, when the federal executive does an act, or the federal legislature passes a law, the question arises, Is the power to do this act or pass this law one of the powes which the people have by the Constitution delegated to their agents? The power may never have been exerted before. It may not be found expressed, in so many words, in the Constitution. Nevertheless it may, upon the true construction of that instrument, taking one clause with another, be held to be therein contained.
Now the doctrines laid down by Chief Justice Marshall, and on which the courts have constantly since proceeded, may be summed up in two propositions.
1. Every power alleged to be vested in the national government, or any organ thereof, must be affirmatively shown to have been granted. There is no presumption in favour of the existence of a power; on the contrary, the burden of proof lies on those who assert its existence, to point out something in the Constitution which, either expressly or by necessary implication, confers it. Just as an agent, claiming to act on behalf of his principal, must make out by positive evidence that his principal gave him the authority he relies on; so Congress, or those who rely on one of its statutes, are bound to show that the people have authorized the legislature to pass the statute. The search for the power will be conducted in a spirit of strict exactitude, and if there be found in the Constitution nothing which directly or impliedly conveys it, then whatever the executive or legislature of the national government, or both of them together, may have done in the persuasion of its existence, must be deemed null and void, like the act of any other unauthorized agent.7
2. When once the grant of a power by the people to the national government has been established, that power will be construed broadly. The strictness applied in determining its existence gives place to liberality in supporting its application. The people—so Marshall and his successors have argued—when they confer a power, must be deemed to confer a wide discretion as to the means whereby it is to be used in their service. For their main object is that it should be used vigorously and wisely, which it cannot be if the choice of methods is narrowly restricted; and while the people may well be chary in delegating powers to their agents, they must be presumed, when they do grant these powers, to grant them with confidence in the agents’ judgment, allowing all that freedom in using one means or another to attain the desired end which is needed to ensure success.8 This, which would in any case be the common-sense view, is fortified by the language of the Constitution, which authorizes Congress “to make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this Constitution in the Government of the United States, or in any department or office thereof.” The sovereignty of the national government, therefore, “though limited to specified objects, is plenary as to those objects” 9 and supreme in its sphere. Congress, which cannot go one step beyond the circle of action which the Constitution has traced for it, may within that circle choose any means which it deems apt for executing its powers, and is in its choice of means subject to no review by the courts in their function of interpreters, because the people have made their representatives the sole and absolute judges of the mode in which the granted powers shall be employed. This doctrine of implied powers, and the interpretation of the words “necessary and proper,” were for many years a theme of bitter and incessant controversy among American lawyers and publicists.10 The history of the United States is in a large measure a history of the arguments which sought to enlarge or restrict its import. One school of statesmen urged that a lax construction would practically leave the states at the mercy of the national government, and remove those checks on the latter which the Constitution was designed to create; while the very fact that some powers were specifically granted must be taken to import that those not specified were withheld, according to the old maxim expressio unius exclusio alterius, which Lord Bacon concisely explains by saying, “as exception strengthens the force of a law in cases not excepted, so enumeration weakens it in cases not enumerated.” It was replied by the opposite school that to limit the powers of the government to those expressly set forth in the Constitution would render that instrument unfit to serve the purposes of a growing and changing nation, and would, by leaving men no legal means of attaining necessary but originally uncontemplated aims, provoke revolution and work the destruction of the Constitution itself.11
This latter contention derived much support from the fact that there were certain powers that had not been mentioned in the Constitution, but which were so obviously incident to a national government that they must be deemed to be raised by implication.12 For instance, the only offences which Congress is expressly empowered to punish are treason, the counterfeiting of the coin or securities of the government, and piracies and other offences against the law of nations. But it was very early held that the power to declare other acts to be offences against the United States, and punish them as such, existed as a necessary appendage to various general powers. So the power to regulate commerce covered the power to punish offences obstructing commerce; the power to manage the post office included the right to fix penalties on the theft of letters; and, in fact, a whole mass of criminal law grew up as a sanction to the civil laws which Congress had been directed to pass.
The three lines along which this development of the implied powers of the government has chiefly progressed, have been those marked out by the three express powers of taxing and borrowing money, of regulating commerce, and of carrying on war. Each has produced a progeny of subsidiary powers, some of which have in their turn been surrounded by an unexpected offspring. Thus from the taxing and borrowing powers there sprang the powers to charter a national bank and exempt its branches and its notes from taxation by a state (a serious restriction on state authority), to create a system of customhouses and revenue cutters, to establish a tariff for the protection of native industry. Thus the regulation of commerce has been construed to include legislation regarding every kind of transportation of goods and passengers, whether from abroad or from one state to another, regarding navigation, maritime and internal pilotage, maritime contracts, etc., together with the control of all navigable waters not situate wholly within the limits of one state, the construction of all public works helpful to commerce between states or with foreign countries, the power to prohibit immigration, and finally a power to establish a railway commission and control all interstate traffic.13 The war power proved itself even more elastic. The executive and the majority in Congress found themselves during the War of Secession obliged to stretch this power to cover many acts trenching on the ordinary rights of the states and of