Laws of the Sport of Bowls
World Bowls is the recognized International Federation for the Sport of Bowls. World Bowls publishes the Laws of the Sport of Bowls, which is the definitive rule book for lawn bowling. A "Member National Authority" is an organization that represents an individual country within the World Bowls federation (Bowls USA is United States' member national authority.) Each member national authority is permitted to make regulations to cover specific aspects of the game that apply only to their country. So, in the US we follow the "Laws of the Sport of Bowls" as published by World Bowls and as amended by the US-specific domestic regulations. (Whew!)
Rule 23.4: All measurements must be made between the nearest points of the jack and the bowl.