Under Darby, Congress may attack any problem, even one overwhelmingly local, by prohibiting all interstate activity associated with it and then as a means of implementing this interstate transaction ban it can prohibit the local activity.
Much more intelligent dissenting opinions by Rehnquist and Thomas point out that a person is no longer travelling when they stop to establish residency, that a welfare subsidy is just as much an investment in human capital as is college education, and the 'fundamental rights' meant by Privileges and Immunities does NOT mean "every public benefit established by positive law."
The 14th Amendment P&I meant only a select few aspects of national citizenship from the Slaughterhouse Cases until Saenz, the Court didn't have to decide this case based on the 14th Amendment. The Right to Travel has been implied in Substantive Due Process and in fundamental liberties.
42 U.S.C. § 1981.
"Equal rights under the law. All persons
within the jurisdiction of the United States shall have the same right in
every State and Territory to make and enforce contracts, to sue, be
parties, give evidence, and to the full and equal benefit of all laws and
proceedings for the security of persons and property as is enjoyed by
white citizens, and shall be subject to like punishment, pains, penalties,
taxes, licenses, and exactions of every kind, and to no
other."
42 U.S.C. § 1982.
"Property rights of citizens. All citizens of the
United States shall have the same right, in every State and Territory, as is
enjoyed by white citizens thereof to inherit, purchase, lease, sell, hold,
and convey real and personal property."
18 U.S.C. § 242.
"Deprivation of rights under color of law.
Whoever, under color of any law, statute, ordinance, regulation, or custom,
willfully subjects any inhabitant of any State, Territory, or District to
the deprivation of any rights, privileges, or immunities secured or
protected by the Constitution or laws of the United States, or to different
punishments, pains or penalties, on account of such inhabitant being an
alien, or by reason of his color, or race, than are prescribed for the
punishment of citizens, shall be fined not more than $1,000 or imprisoned
not more than one year, or both; and if death results shall be subject to
imprisonment for any term of years or for life."
42 U.S.C. § 1983.
"Civil action for deprivation of rights.
Every person who, under color of any statute, ordinance, regulation, custom,
or usage, of any State or Territory, subjects, or causes to be subjected,
any citizen of the United States or other persons within the jurisdiction
thereof to the deprivation of any rights, privileges or immunities secured
by the Constitution and laws, shall be liable to the person injured in an
action of law, suit in equity, or other proper proceedings for redress."
42 U.S.C. § 1985.
"Conspiracy to interfere with civil rights.
(3)
Depriving persons of rights or privileges
If two or more persons in any
State or Territory conspire or go in disguise on the highway or on the
premises of another, for the purpose of depriving, either directly or
indirectly, any person or class of persons of the equal protection of the
laws, or of equal privileges and immunities under the laws; or for the
purpose of preventing or hindering the constituted authorities of any State
or Territory from giving or securing to all persons within such State or
Territory the equal protection of the laws; or if two or more persons
conspire to prevent by force, intimidation, or threat, any citizen who is
lawfully entitled to vote, from giving his support or advocacy in a legal
manner, toward or in favor of the election of any lawfully qualified person
as an elector for President or Vice President, or as a Member of Congress of
the United States; or to injure any citizen in person or property on account
of such support or advocacy; in any case of conspiracy set forth in this
section, if one or more persons engaged therein do, or cause to be done, any
act in furtherance of the object of such conspiracy, whereby another is
injured in his person or property, or deprived of having and exercising any
right or privilege of a citizen of the United States, the party so injured
or deprived may have an action for the recovery of damages occasioned by
such injury or deprivation, against any one or more of the
conspirators."
18 U.S.C. § 241.
"Conspiracy against rights of citizens. If two or
more persons conspire to injure, oppress, threaten, or intimidate any
citizen in the free exercise or enjoyment of any right or privilege secured
to him by the Constitution or laws of the United States, or because of his
having exercised the same; or
"If two or more persons go on the
highway, or on the premises of another, with intent to prevent or hinder his
free exercise or enjoyment of any right or privilege so secured --
"They shall be fined not more than $10,000 or imprisoned not more than ten
years, or both; and if death results, they shall be subject to imprisonment
for any term of years or for life."