▁of ▁modern ▁regul atory ▁schemes . ▁ ▁As ▁a ▁result , ▁the ▁specification ▁of ▁these ▁details ▁are ▁mostly ▁deleg ated ▁to ▁ag encies ▁for ▁rule making . ▁ ▁Common ▁purposes ▁of ▁rule making ▁include : ▁ ▁Adding ▁scientific ▁expert ise . ▁ ▁For ▁example , ▁in ▁the ▁U . S ., ▁the ▁Federal ▁Food , ▁D rug , ▁and ▁Cos met ic ▁Act ▁out la ws ▁the ▁sale ▁of ▁ad ul ter ated ▁or ▁imp ure ▁dru gs . ▁The ▁act ▁requires ▁that ▁the ▁Department ▁of ▁Health ▁and ▁Human ▁Services ▁prom ul gate ▁reg ulations ▁establish ing ▁which ▁labor atory ▁tests ▁to ▁use ▁to ▁test ▁the ▁pur ity ▁of ▁each ▁drug . ▁ ▁Adding ▁implementation ▁detail . ▁ ▁Legisl ation ▁on ▁autom obile ▁fuel ▁efficiency , ▁for ▁example , ▁often ▁deleg ates ▁the ▁development ▁of ▁the ▁actual ▁engine ▁tests ▁used ▁to ▁calculate ▁' city ▁mile age ' ▁and ▁' high way ▁mile age '. ▁ ▁Adding ▁industry ▁expert ise . ▁ ▁The ▁U . S . ▁C lean ▁Air ▁Act ▁and ▁C lean ▁Water ▁Act ▁require ▁the ▁United ▁States ▁Environment al ▁Prote ction ▁Agency ▁to ▁determine ▁the ▁appropriate ▁em issions ▁control ▁techn ologies ▁on ▁an ▁industry - by - indust ry ▁basis . ▁ ▁Adding ▁flex ibility . ▁ ▁More ▁detailed ▁reg ulations ▁allow ▁for ▁more ▁nu anced ▁approaches ▁to ▁various ▁conditions ▁than ▁a ▁single ▁legisl ative ▁standard ▁could . ▁ ▁Moreover , ▁reg ulations ▁tend ▁to ▁be ▁more ▁easily ▁changed ▁as ▁new ▁data ▁or ▁techn ologies ▁emer ge . ▁ ▁F inding