[Ken H]

The best discussion of the Privileges or Immunities Clause I have come across is the dissent by Justice Thomas in Saenz v Roe. Excerpt:

Because I believe that the demise of the Privileges or Immunities Clause has contributed in no small part to the current disarray of our Fourteenth Amendment jurisprudence, I would be open to reevaluating its meaning in an appropriate case.

http://www.law.cornell.edu/supct/html/historics/USSC_CR_0526_0489_ZD1.html