If this Act provides that Torres Strait Islanders be generally in agreement with a grant, consent or agreement about Torres Strait Islander land, the agreement of the Torres Strait Islanders is taken to have been given when—
(a) if there is a particular process of decision-making that, under the Island custom of the Torres Strait Islanders, must be complied with for decisions of that kind—the decision was made under the process; or
(b) otherwise—the decision was made under the process of decision-making agreed to and adopted by the Torres Strait Islanders for the decision or for decisions of that kind.