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 * * *" Madison, writing in _The
Federalist_,[133] adverted to the confusion engendered by use of the
different terms "free inhabitants, free citizens," and "people" and by
"superadding to 'all privileges and immunities of free citizens--all the
privileges of trade and commerce,' * * *" The more concise phraseology
of article IV, however, did little to dispel the uncertainty. In the
Slaughter-House Cases,[134] Justice Miller suggested that it was to be
regarded as the compendious equivalent of the earlier version: "There
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 the Confederation we have some of these
specifically mentioned, and enough perhaps to give some general ideal of
the class of civil rights meant by the phrase."[135]

THEORIES AS TO ITS PURPOSE

First and last, at least four theories have been proffered regarding the
purpose of this clause. The first is that the clause is a guaranty to
the citizens of the different States of equal treatment by Congress--is,
in other words, a species of equal protection clause binding on the
National Government. The second is that the clause is a guaranty to the
citizens of each State of all the privileges and immunities of
citizenship that are enjoyed in any State by the citizens thereof,--a
view which, if it had been accepted at the outset, 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
Fourteenth Amendment. The third theory of the clause is that it
guarantees to the citizen of any State the rights which he enjoys as
such even when sojourning in another State, that is to say, enables him
to carry with him his rights of State citizenship throughout the Union,
without embarrassment by State lines. Finally, the clause is interpreted
as merely forbidding any State to discriminate against citizens of other
States in favor of its own. Though the first theory received some
recognition in the Dred Scott Case,[136] particularly in the opinion of
Justice Catron,[137] it is today obsolete.