Constraints on wise use are not always apparent from primary legislation, which often takes
the form of a general enabling instrument. For reasons of administrative efficiency, most countries
use secondary legislation (implementing regulations or statutory instruments) to establish detailed
operational criteria, thresholds, permitted categories of development or exemptions for the
implementation of the relevant Act. It may be only at this level of detail that the adequacy or
inadequacy of permit systems becomes clear and the cumulative impact of activities exempt from
the permit requirement can be assessed.