Theoretically, Louisiana is a civil-law jurisdiction. This means that our primary sources of law are legislation and custom. Theoretically, it also means that we don’t recognize stare decisis: the idea that an appellate decision creates binding law for the appellate court and all lower courts under its jurisdiction.
But, as anyone who has practiced in the appellate courts for a few years knows, the reality does not conform exactly to the theory. Over at the New Orleans Bar Association web site, Bruce Dean has posted a short, informative, and entertaining article explaining why, despite our civilian heritage, caselaw matters in Louisiana.