This article explains the meaning of the U.S. Constitution's Privileges and Immunities Clause of Article IV, as the Founders understood it. It explains that the terms "privileges" and "immunities" had well-understood content in 18th century law---as benefits created by government. The Clause protects states from discriminating against visitors as to the benefits of citizenship (such as access to the courts), but does not address "natural rights" such as freedom of speech and religion.
Robert G. Natelson. "The Original Meaning of the Privileges and Immunities Clause" Georgia Law Review
Vol. 43 (2009)
Available at: http://works.bepress.com/robert_natelson/22/