From the United States Constitution, Article IV, Section II, Clause I:
The Citizens of each State shall be entitled to all Privileges and Immunities of Citizens in the several States.
In the many times this clause was referenced in the courts, it was mostly associated with the rights of a visiting citizen from another state still being protected.
Why has it never been read as recognition of the Federal government's role in protecting the rights of citizens within their own State? Were there political machinations that prevented such a reading, possibly due to the importance of State sovereignty at the time of ratification?
These words were then paraphrased in the first section of the 14th Amendment.
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States,...
Combined with the fifth section of the same amendment, this was seen as formerly empowering the Federal government to protect individual rights. I've seen thus as just a reiteration of the restriction already existing on State government. However, it is viewed as being read out of the constitution by the Slaughter House cases of 1873, not rising again until McDonald v Chicago of 2010.
So, why was the "Privileges and Immunities" clause never reviewed, referenced or addressed?