They were of various kinds, namely, the following: (1) Edicta; (2) decreta; (3) re- scripta, called also “epistolw.” Sometimes they were general, and intended to form a precedent for other like cases ; at other times they were special, particular , or individual , (personates.) and not intended to form a precedent. The emperor had this power of irresponsible enactment by virtue of a certain lex rer/ia, whereby he was made the fountain of justice and of mercy. Brown. Constitutiones tempore posteriores po- tiores sunt his qua: ipsas praecesserunt. Dig. 1, 4, 4. Later laws prevail over those which preceded them
Black’s Law Online Dictionary
