it a State may legislate to prevent the spread of crime, or pauperism, or disturbance of the peace. It may exclude from its limits convicts, paupers, idiots, and lunatics, and persons likely to become a public charge, as well as persons afflicted by contagious or infectious diseases; a right founded, as intimated in the Passenger Cases (7 How., 283), by Mr. Justice Greer, in the sacred law of self-defense (vide 3 Sawyer, 283). The same principle, it may also be conceded, would justify the exclusion of the property dangerous to the property of citizens of the State; for example, aniinals having contagious or infectious diseases. All these exertions of power are in immediate connection with the protection of persons and property against noxious acts of other persons, or such a use of property as is injurious to the property of others. They are self-defensive.

But whatever may be the nature and reach of the police power of a State, it cannot be exercised over a subject confided exclusively to Congress by the Federal Constitution. It cannot invade the domain of the national Government. It was said in Henderson et al. v. Mayor of the City of New York et al., supra., to "be clear from the nature of our complex form of Government, that whenever the statute of a State invades the domain of legislation which belongs exclusively to the Congress of the United States, it is void, no matter under what class of powers it may fall, or how closely allied it may be to powers conceded to belong to the States." Substantially the same thing was said by Chief Justice Marshall in Gibbons v. Ogden (9 Wheat., 1). Neither the unlimited powers of a State to tax, nor any of its large police powers, can be exercised to such an extent as to work a practical assumption of the powers properly conferred upon Congress by the Constitution. Many acts of a State may, indeed, affect commerce, without amounting to a regulation of it, in the constitutional sense of the term. And it is sometimes difficult to define the distinction between that which merely affects or influences and that which regulates or furnishes a rule for conduct. There is no such difficulty in the present case. While we unhesitatingly admit that a State may pass sanitary laws and laws for the protection of life, liberty, health, or property within its borders, while it may prevent persons and animals suffering under contagious or infectious diseases, or convicts, &c., from entering the State; while for the purpose of self-protection it may establish quarantine, and reasonable inspection laws, it may not interfere with transportation into or through the State, beyond what is absolutely necessary for its self-protection. It may not, under cover of exerting its police power, substantially prohibit or burden either foreign or inter-State commerce. Upon this subject the cases in 92 U. S., to which we have referred, are very instructive. In Henderson v. The Mayor, &c., the statute of New York was defended as a police regulation to protect the State against the influx of foreign paupers, but was held to be unconstitutional, because its practical result was to impose a burden upon all passengers from foreign countries, and it was laid down that "in whatever language a statute may be framed, its purpose must be determined by its natural and reasonable effect." The reach of the statute was far beyond its professed object, and far into the realm which is within the exclusive jurisdiction of Congress. So in case of Chi Lung v. Freeman, where the pretense was the exclusion of lewd women, but as the statute was more far-reaching and affected other immigrants, not of any class which the state could lawfully exclude, we held it unconstitutional. Neither of these cases denied the right of a State to protect herself against paupers, convicted criminals, or lewd women, by necessary and proper laws, in the absence of legislation by Congress, but it was ruled that the right could only arise from vital necessity, and that it could not be carried beyond the scope of that necessity. These cases, it is true, speak only of laws affecting the entrance of persons into the State, but the constitutional doctrines they maintain are equally applicable to inter-State transportation of property. They deny validity to any State legislation professing to be an exercise of police power for protection against evils from abroad, which is beyond the necessity for its exercise wherever it interferes with the rights and powers of the Federal Government.

Tried by this rule, the statute of Missouri is a plain intrusion upon the exclusive domain of Congress. It is not a quarantine law. It is not an inspection law. It says to all natural persons and to all transportation companies, " You shall not bring into the State any Texas cattle or any Mexican cattle or Indiau cattle, between March 1 and December 1, in any year, no matter whether they are free from disease or not, no matter whether they may do an injury to the inhabitants of the State or not; and if you do bring them in even for the purpose of carrying them through the State without unloading them, you shall be subject to extraordinary liabilities." Such a statute, we do not doubt, is beyond the power of a State to enact. To hold otherwise would be to ignore one of the leading objects which the Constitution of the United States was designed to secure.

In coming to such a conclusion, we have not overlooked the decisions of very respectable courts in Illinois, where statutes similar to the one we have before us have been sustained. (Yeazel v. Alexander, 58 Ill., 254.) Regarding the statutes as mere police regulations, intended to protect domestic cattle against infectious disease,

those courts have refused to inquire whether the prohibition did not extend beyond the danger to be apprehended, and whether, therefore, the statutes were not something more than exertions of police power That inquiry, they have said, was for the legislature and not for the courts. With this we cannot concur. The police power of a State cannot obstruct foreign commerce or inter-State commerce beyond the necessity for its exercise; and under color of it objects not within its scope cannot be secured at the expense of the protection afforded by the Federal Constitution. And as its range sometimes comes very near to the field committed by the Constitution to Congress, it is the duty of the courts to guard vigilantly against any needless intrusion.

Since the above decision was rendered various attempts have been made to avoid its application by changing the phraseology of the laws and regulations, by calling them inspection and quarantine laws, and by insisting that the reserved police powers of the States are the source from which the authority is derived. It is not probable, however, that these State regulations are made in any way more nearly constitutional by such changes. In the case of Henderson v. Wickam it was held that:

In whatever language a statute may be framed, its purpose must be determined by its natural and reasonable effect. (92 U. S., 259.)

The following language used in the same decision makes it still more plain that a law designed by a State to accomplish this object would meet with the same objection in the Supreme Court, no matter in what terms it should be framed:

This power, frequently referred to in the decisions of this court, has been, in general terms, somewhat loosely called the police power. It is not necessary for the course of this discussion to attempt to define it more accurately than it has been defined already. It is not necessary, because whatever may be the nature and extent of that power, when not otherwise restricted, no definition of it and no urgency for its use can authorize a State to exercise it in regard to a subject-matter which has been confided exclusively to the discretion of Congress by the Constitution.

Nothing is gained in the argument by calling it police power. Very many statutes, when the authority on which their enactments rest is examined, may be referred to different sources of power, and supported equally well under any of them. A statute may at the same time be an exercise of the taxing power and of the power of eminent domain. A statute punishing counterfeiting may be for the protection of the private citizen against fraud, and a measure for the protection of the currency and for the safety of the Government which issues it. It must occur very often that the shading which marks the line between one class of legislation and another is very nice and not easily distinguishable.

But however difficult this may be, it is clear from the nature of our complex form of government that whenever the statute of a State invades the domain of the legislation which belongs exclusively to the Congress of the United States it is void, no matter under what class of powers it may fall or how closely allied to powers conceded to belong to the States. (92 U. S., 259.)

If such laws are necessary to protect the States and regulations of commerce, it follows that the States are powerless to prevent the introduction of contagious diseases, and that the required measures are so intimately related to regulations of inter-State commerce that Congress alone can act effectually to secure this result.

Conceding, then, that measures for the control and extirpation of pleuro-pneumonia, and similar contagious diseases of animals, may be properly construed as regulations of inter-State and foreign commerce, we have still to inquire if, under the authority granted in the Constitution to regulate this commerce, the power of Congress can extend into the interior of the States and enable Federal officers to carry out the details for the extirpation of such diseases. It is admitted in the animal industry law that the owners of affected animals and the officers of transportation companies may be notified of the existence of a contagious disease, and that if they then ship such animals from one State

or Territory into another they will be liable to the penalties imposed by that law. But before such parties can be notified of the existence of disease, it is necessary for the inspectors of the Bureau of Animal Industry to discover it, and hence it is necessary to make inspections. To make inspections, however, it is necessary to have authority to go within the Territory of a State, to enter upon private premises and to examine the stock. As a matter of fact, therefore, the penalty provided for the shipment of affected cattle from one State into another cannot be enforced without power to make inspections and to discover the existence and nature of disease. This attempt to so regulate commerce as to prevent the dissemination of dangerous maladies from one State or Territory into another, must remain imperfect and of little practical value unless the additional authority is given to make inspections within the several States and Territories. The question for consideration may, consequently, be stated in this form: To what extent can Congress enforce its authority within the States for the accomplishment of an object (viz., the regulation of inter-State commerce) which is admitted to be within the exclusive jurisdiction of Congress? The decisions of the Supreme Court have been very explicit on this subject, and I take the liberty of quoting some of them at considerable length because of the great importance of the question at issue.

Chief Justice Marshall, in the case of Gibbons v. Ogden, (22 U. S., 186-222), said:

This instrument contains an enumeration of powers expressly granted by the people to their Government. It has been said that these powers ought to be construed strictly. But why ought they to be so construed? Is there one sentence in the Constitution which gives countenance to this rule? In the last of the enumerated powers, that which grants expressly the means of carrying all others into execution, Congress is authorized "to make all laws which shall be necessary and proper" for the purpose. But this limitation on the means which may be used is not extended to the powers which are conferred; nor is there one sentence in the Constitution which has been pointed out by the gentlemen of the bar, or which we have been able to discover, that prescribes this rule. We do not, therefore, think ourselves justified in adopting it. What do gentlemen mean by a strict construction? If they contend only against that enlarged construction which would extend words beyond their natural and obvious import, we might question the application of the term, but should not controvert the principle. If they contend for that narrow construction which, in support of some theory not to be found in the Constitution, would deny to the Government those powers which the words of the grant, as usually understood, import, and which are consistent with the general views and objects of the instrument; for that narrow construction, which would cripple the Government and render it unequal to the objects for which it is declared to be instituted, and to which the powers given, as fairly understood, render it competent; then we cannot perceive the propriety of this strict construction, nor adopt it as the rule by which the Constitution is to be expounded. As men whose intentions require no concealment generally employ the words which most directly and aptly express the ideas they intend to convey, the enlightened patriots who framed our Constitution, and the people who adopted it, must be understood to have employed words in their natural sense, and to have intended what they have said. If, from the imperfection of human language, there should be serious doubts respecting the extent of any given power, it is a wellsettled rule that the objects for which it was given, especially when those objects are expressed in the instrument itself, should have great influence in the construction. We know of no reason for excluding this rule from the present case. The grant does not convey power which might be beneficial to the grantor, if retained by himself, or which can inure solely to the benefit of the grantee, but is an investment of power for the general advantage, in the hands of agents selected for that purpose, which power can never be exercised by the people themselves, but must be placed in the hands of agents, or lie dormant. We know of no rule for construing the extent of such powers, other than is given by the language of the instrument which confers them, taken in connection with the purposes for which they were conferred.

The words are: Congress shall have power to regulate commerce with foreign nations, and among the several States, and with the Indian tribes.

The subject to be regulated is commerce; and our Constitution being, as was aptly said at the bar, one of enumeration and not of definition, to ascertain the extent of

the power it becomes necessary to settle the meaning of the word. The counsel for the appellee would limit it to traffic, to buying and selling, or the interchange of commodities, and do not admit that it comprehends navigation. This would restrict a general term, applicable to many objects to one of its significations. Commerce, undoubtedly, is traffic, but it is something more; it is intercourse. It describes the commercial intercourse between nations, and parts of nations, in all its branches, and is regulated by presenting rules for carrying on that intercourse (pp. 187–190).

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To what commerce does this power extend? The Constitution informs us, to commerce "with foreign nations, and among the several States, and with the Indian tribes."

It has, we believe, been universally admitted that these words comprehend every species of commercial intercourse between the United States and foreign nations. No sort of trade can be carried on between this country and any other to which the power does not extend. It has been truly said that commerce, as the word is used in the Constitution, is a unit, every part of which is indicated by the term.

If this be the admitted meaning of the word in its application to foreign nations, it must carry the same meaning throughout the sentence and remain a unit, unless there be some plain, intelligible cause which alters it.

The subject to which the power is next applied is to commerce among the several States." The word "among" means intermingled with. A thing which is among others is intermingled with them. Commerce among the States cannot stop at the external boundary line of each State, but may be introduced into the interior.

It is not intended to say that these words comprehend that commerce which is completely internal, which is carried on between man and man in a State or between different parts of the same State, and which does not extend to or affect other States. Such a power would be inconvenient, and is certainly unnecessary.

Comprehensive as the word "among" is, it may be very properly restricted to that commerce which concerns more States than one. The phrase is not one which would probably have been selected to indicate the completely interior traffic of a State, because it is not an apt phrase for that purpose; and the enumeration of the particular classes of commerce to which the power was to be extended would not have been made had the intention been to extend the power to every description. The enumeration presupposes something not enumerated; and that something, if we regard the language or the subject of the sentence, must be the exclusively internal commerce of the State. The genius and character of the whole Government seem to be that its action is to be applied to all the external concerns of the nation, and to those internal concerns which affect the States generally, but not to those which are completely within a particular State, which do not affect other States, and with which it is not necessary to interfere, for the purpose of executing some of the general powers of the Government. The completely internal commerce of a State, then, may be considered as reserved for the State itself.

But, in regulating commerce with foreign nations, the power of Congress does not stop at the jurisdictional lines of the several States. It would be a very useless power if it could not pass those lines. The commerce of the United States with foreign nations is that of the whole United States. Every district has a right to participate in it. The deep streams which penetrate our country in every direction pass through the interior of almost every State in the Union, and furnish the means of exercising this right. If Congress has the power to regulate it, that power must be exercised whenever the subject exists. If it exists within the States, if a foreign voyage may commence or terminate at a port within a State then the power of Congress may be exercised within a State.

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This principle is, if possible, still more clear when applied to commerce among the several States." They either join each other, in which case they are separated by a mathematical line, or they are remote from each other, in which case other States lie between them. What is commerce "among" them, and how is it to be conducted? Can a trading expedition between two adjoining States commence and terminate outside of each? And if the trading intercourse be between two States remote from each other, must it not commence in one, terminate in the other, and probably pass through a third? Commerce among the States must of necessity be commerce with the States. In the regulation of trade with the Indian tribes, the action of the law, especially when the Constitution was made, was chiefly within a State. The power of Congress, then, whatever it may be, must be exercised within the territorial jurisdiction of the several States. The sense of the nation on this subject is unequivocally manifested by the provisions made in the laws for transporting, by land, between Baltimore and Providence, between New York and Philadelphia, and between Philadelphia and Baltimore.

We are now arrived at the inquiry, What is this power?

It is the power to regulate; that is, to prescribe the rule by which commerce is to be governed. This power, like all others vested in Congress, is complete in itself,

may be exercised to its utmost extent, and acknowledges no limitations, other than are prescribed in the Constitution. These are expressed in plain terms, and do not affect the questions which arise in this case, or which have been discussed at the bar. If, as has always been understood, the sovereignty of Congress, though limited to specified objects, is plenary as to those objects, the power over commerce with foreign nations and among the several States, is vested in Congress as absolutely as it would be in a single government, having in its constitution the same restrictions on the exercise of the power as are found in the Constitution of the United States. (pp. 193– 197.)

But the inspection laws are said to be regulations of commerce, and are certainly recognized in the Constitution, as being passed in the exercise of a power remaining with the States.

That inspection laws may have a remote and considerable influence on commerce, will not be denied, but that a power to regulate commerce is the source from which the right to pass them is derived, cannot be admitted. The object of inspection laws is to improve the quality of articles produced by the labor of the country; to fit them for exportation; or, it may be, for domestic use. They act upon the subject before it becomes an article of foreign commerce, or of commerce among the States, and prepare it for that purpose. They form a portion of that immense mass of legislation which embraces everything within the territory of a State not surrendered to the General Government; all which can be most advantageously exercised by the States themselves. Inspection laws, quarantine laws, health laws of every description, as well as laws for regulating the internal commerce of a State, and those which respect turnpike roads, ferries, &c., are component parts of this mass.

No direct general power over these objects is granted to Congress, and, consequently, they remain subject to State legislation. If the legislative power of the Union can reach them it must be for national purposes-it must be where the power is expressly given for a special purpose, or is clearly incidental to some power which is expressly given. It is obvious that the Government of the Union, in the exercise of its express powers-that, for example, of regulating commerce with foreign nations and among the States--may use means that may also be employed by a State, in the exercise of its acknowledged power-that, for example, of regulating commerce within the State. If Congress license vessels to sail from one port to another in the same State the act is supposed to be necessarily incidental to the power expressly granted to Congress, and implies no claim of a direct power to regulate the purely internal commerce of a State, or to act directly on its system of police. So if a State, in passing laws on subjects acknowledged to be within its control, and with a view to those subjects shall adopt a measure of the same character with one which Congress may adopt, it does not derive its authority from the particular power which has been granted, but from some other, which remains with the State, and may be executed by the same means. All experience shows that the same measures, or measures scarcely distinguishable from each other, may flow from distinct powers, but this does not prove that the powers themselves are identical. Although the means used in their execution may sometimes approach each other so nearly as to be confounded, there are other situations in which they are sufficiently distinct to establish their individuality (pp. 203-204).

The acts of Congress, passed in 1796 and 1799 (2 U. S. L., p. 545; 3 U. S. L., p. 126), empowering and directing the officers of the General Government to conform to and assist in the execution of the quarantine and health laws of the State, proceed, it is said, upon the idea that these laws are constitutional. It is undoubtedly true that they do proceed upon that idea; and the constitutionality of such laws has never, so far as we are informed, been denied. But they do not imply an acknowledgment that a State may rightfully regulate commerce with foreign nations, or among the States, for they do not imply that such laws are an exercise of that power, or enacted with a view to it. On the contrary they are treated as quarantine and health laws, are so denominated in the acts of Congress, and are considered as flowing from the acknowledged power of a State, to provide for the health of its citizens. But, as it was apparent that some of the provisions made for this purpose, and in virtue of this power might interfere with and be affected by the laws of the United States, made for the regulation of commerce, Congress in that spirit of harmony and conciliation which ought always to characterize the conduct of governments standing in the relation which that of the Union and those of the States bear to each other, has directed its officers to aid in the execution of these laws; and has in some measure adapted its own legislation to this object by making provisions in aid of those of the States. But in making these provisions, the opinion is unequivocally manifested that Congress may control the State laws, so far as it may be necessary to control them for the regulation of commerce (pp. 205-206).