The rules of origin are enforced through a certificate of origin that is issued by authorised agencies of the trading partner. An exporter cannot avail of the customs tariff preferences under the FTA without submitting this certificate of origin from the authorised agency.
International Trade Law includes the appropriate rules and customs for handling trade between countries. However, it is also used in legal writings as trade between private sectors, which is not right.
This branch of law is now an independent field of study as most governments has become part of the world trade, as members of the World Trade Organization (WTO).
Since the transaction between private sectors of different countries is an important part of the WTO activities, this latter branch of law is now a very important part of the academic works and is under study in many universities across the world.