Lex

[Latin, Law.] In medieval JURISPRUDENCE ,a body or collection of various laws peculiar to a given nation or people; not a code in the modern sense, but an aggregation or collection of laws not codified or systematized. Also, a similar collection of laws relating to a general subject, and not peculiar to any one people.

In modern U.S. and English jurisprudence this term signifies a system or body of laws, written or unwritten, applicable to a particular case or question regarded as local or unique to a particular state, country, or jurisdiction.