This is debatable. Babylon had the first known written law system and is the origin of the phrase "Written in Stone" as the laws were written on stone tablets inside the temples used to adjudicate law, in most cases. This was called the Code of Hammurabi and contained 282 written laws; dated 1795 B.C. The Jewish religion also contained 613 "Commandments" (later narrowed to 10) known as the Law of Moses - dated 1391 B.C. Rome also produced a written law system, and coined the term "Statutes" for that law; dated 753 B.C. Each of these systems used elements of the others, and or added to them to improve the way they functioned. The 'origin' depends on more specific parameters.
The origin of the phrase "Written in Stone" most likely comes from the Law of Hammurabi which states that the law as written cannot be changed by anyone that follows and it was 'written in stone' so that it could not be changed. Its alternate saying, linked below, is something that is changeable.
Bernard O'Connor has written: 'The law of geographical indications' -- subject(s): Marks of origin, Foreign trade regulation, Intellectual property (International law)
W. T. S. Daniels has written: 'The history and origin of the Law reports' -- subject- s -: Incorporated Council of Law Reporting for England and Wales, Law reporting
William A. Hunter has written: 'Introduction to Roman law' 'True origin of the criminal laws affecting the working-classes'
William Thomas Shave Daniel has written: 'The history and origin of the Law reports, together with a compilation of various documents shewing the progress and result of proceedings taken for their establishment' 'The History and Origin of the Law Reports: Together with a Compilation of Various Documents ..'
Frederick Davis has written: 'The etymology of some Derbyshire place-names' -- subject(s): Geographical Names 'Commercial law, its origin and early incidents' -- subject(s): Commercial law
Harald Schlossmacher has written: 'Grundrechtliche Aspekte geographischer Herkunftsangaben' -- subject(s): Geographical Names, Law and legislation, Marks of origin
Dev Gangjee has written: 'Relocating the law of geographical indications' -- subject(s): LAW / Intellectual Property / General, Agreement on Trade-Related Aspects of Intellectual Property Rights, Intellectual property (International law), Marks of origin
Common Law
Jacob Phillips has written: 'An inquiry into the origin and influence of the controverted rule of law called the rule in Shelley's case' -- subject(s): Shelley's case, Rule in
Contract law is just a body of law regarding... well... contracts.
Vern E. Hauck has written: 'Arbitrating race, religion, and national origin discrimination grievances' -- subject(s): Law and legislation, Discrimination in employment, Grievance arbitration