All World Rugby Laws of the Game can be found here.
Rugby Ontario Modified Laws
*Under-16 & Under-18 age grades follow World Rugby Under-19 Laws
From time to time, National Unions request clarification of laws from World Rugby. When World Rugby completes the clarification, they distribute the document, and send it back to all nations. These can be very important, as they clear up issues with laws and interpretation of laws. They must be read and understood, similar to actual laws, by coaches, players, referees, and spectators.
You can find a listing of all law clarifications here.
2016 World Rugby Law Clarifications
2016 World Rugby Law Amendments
Law Clarification 1:2016