Private International Law (often called "conflict of laws") governs the choice of law to apply when conflicts exist in national domestic laws related to private transactions between those nations. Marci Hoffman and Katherine Topolos, International Legal Research Tutorial: Private International Law (last visited Jan. 23, 2013).
It often arises in disputes involving:
Private international law is the body of conventions, model laws, national laws, legal guides, and other documents and instruments that regulate private relationships across national borders. Private international law has a dualistic character, balancing international consensus with domestic recognition and implementation, as well as balancing sovereign actions with those of the private sector." Louise Tsang, ASIL Electronic Resource Guide: Private International Law (last visited Jan. 23, 2013)