<P> Under Louisiana's codified system, the Louisiana Civil Code, private law--that is, substantive law between private sector parties--is based on principles of law from continental Europe, with some common law influences . These principles derive ultimately from Roman law, transmitted through French law and Spanish law, as the state's current territory intersects the area of North America colonized by Spain and by France . Contrary to popular belief, the Louisiana code does not directly derive from the Napoleonic Code, as the latter was enacted in 1804, one year after the Louisiana Purchase . However, the two codes are similar in many respects due to common roots . </P> <P> Louisiana's criminal law largely rests on English common law . Louisiana's administrative law is generally similar to the administrative law of the U.S. federal government and other U.S. states . Louisiana's procedural law is generally in line with that of other U.S. states, which in turn is generally based on the U.S. Federal Rules of Civil Procedure . </P> <P> Historically notable among the Louisiana code's differences from common law is the role of property rights among women, particularly in inheritance gained by widows . </P> <P> The U.S. state of California has a system based on common law, but it has codified the law in the manner of the civil law jurisdictions . The reason for the enactment of the California Codes in the 19th century was to replace a pre-existing system based on Spanish civil law with a system based on common law, similar to that in most other states . California and a number of other Western states, however, have retained the concept of community property derived from civil law . The California courts have treated portions of the codes as an extension of the common - law tradition, subject to judicial development in the same manner as judge - made common law . (Most notably, in the case Li v. Yellow Cab Co., 13 Cal. 3d 804 (1975), the California Supreme Court adopted the principle of comparative negligence in the face of a California Civil Code provision codifying the traditional common - law doctrine of contributory negligence .) </P>

Who helped establish common law in the united states