Jurisdiction’s basis of applying law consists of (1) A constitution, written or oral; (2) Primary legislation, statutes, and laws; authorized by constitutionally authorized legislative body; (3) Primary legislation authorized body enacts subsidiary legislation or bylaws; (4) Traditional practices upheld by the courts; (5) Civil, common, Roman, or other code of law as source of such principles or practices.
TLD Example: The American legal system traces its origins to the principles of law and jurisprudence of English common law.