Article IV, Section 2, Clause 1:
The Citizens of each State shall be entitled to all Privileges and Immunities of Citizens in the several States.
The primary purpose of this clause, like the clauses between which it is located . . . was to help fuse into one Nation a collection of independent sovereign States. 1 Precedent for this clause was a much wordier and a somewhat unclear 2 clause of the Articles of Confederation.
The better to secure and perpetuate mutual friendship and intercourse among the people of the different States in this Union, the free inhabitants of each of these States, paupers, vagabonds and fugitives from justice excepted, shall be entitled to all privileges and immunities of free citizens in the several States; and the people of each State shall have free ingress and regress to and from any other State, and shall enjoy therein all the privileges of trade and commerce, subject to the same duties, impositions and restrictions as the inhabitants thereof respectively . . . . 3 In the Convention, the present clause was presented, reported by the Committee on Detail, and adopted all in the language ultimately approved. 4 Little commentary was addressed to it, 5 and we may assume with Justice Miller that
[t]here can be but little question that the purpose of both these provisions is the same, and that the privileges and immunities intended are the same in each. In the Articles of Confederation we have some of these specifically mentioned, and enough perhaps to give some general idea of the class of civil rights meant by the phrase. 6 At least four theories have been proffered regarding the purpose of this clause. First, the clause is a guaranty to the citizens of the different states of equal treatment by Congress; in other words, it is a species of equal protection clause binding on the National Government. Though it received some recognition in the Dred Scott case, 7 particularly in the opinion of Justice Catron, 8 this theory is today obsolete. 9 Second, the clause is a guaranty to the citizens of each state of the natural and fundamental rights inherent in the citizenship of persons in a free society, the privileges and immunities of free citizens, which no state could deny to citizens of other states, without regard to the manner in which it treated its own citizens. This theory found some expression in a few state cases 10 and best accords with the natural law-natural rights language of Justice Washington in Corfield v. Coryell. 11
If it had been accepted by the Court, this theory might well have endowed the Supreme Court with a reviewing power over restrictive state legislation as broad as that which it later came to exercise under the Due Process and Equal Protection Clauses of the Fourteenth Amendment, but it was firmly rejected by the Court. 12 Third, the clause guarantees to the citizen of any state the rights which he enjoys as such even when he is sojourning in another state; that is, it enables him to carry with him his rights of state citizenship throughout the Union, unembarrassed by state lines. This theory, too, the Court rejected. 13 Fourth, the clause merely forbids any state to discriminate against citizens of other states in favor of its own. It is this narrow interpretation that has become the settled one.
It was undoubtedly the object of the clause in question to place the citizens of each State upon the same footing with citizens of other States, so far as the advantages resulting from citizenship in those States are concerned. It relieves them from the disabilities of alienage in other States; it inhibits discriminating legislation against them by other States; it gives them the right of free ingress into other States, and egress from them; it insures to them in other States the same freedom possessed by the citizens of those States in the acquisition and enjoyment of property and in the pursuit of happiness; and it secures to them in other States the equal protection of their laws. 14
The recent cases emphasize that interpretation of the clause is tied to maintenance of the Union.
Some distinctions between residents and nonresidents merely reflect the fact that this is a Nation composed of individual States, and are permitted; other distinctions are prohibited because they hinder the formation, the purpose, or the development of a single Union of those States. Only with respect to those ‘privileges’ and ‘immunities’ bearing upon the vitality of the Nation as a single entity must the State treat all citizens, resident and nonresident, equally. 15 Although the clause
was intended to create a national economic union, it also protects noneconomic interests relating to the Union. 16
Hostile discrimination against all nonresidents infringes the clause, 17 but controversies between a state and its own citizens are not covered by the provision. 18 However, a state discrimination in favor of residents of one of its municipalities implicates the clause, even though the disfavored class consists of in-state as well as out-of-state inhabitants. 19 The clause should not be read so literally, the Court held, as to permit states to exclude out-of-state residents from benefits through the simple expediency of delegating authority to political subdivisions. 20 A violation can occur whether or not a statute explicitly discriminates against out-of-state interests. 21