What is Constitutiones?

Legal Definition
Laws promulgated, i. e., enacted, by the Roman Emperor. They were of various kinds, namely, the following:

(1) Edicta;

(2) decreta;

(3) rescripta, called also "epistoloe." Sometimes they were general, and intended to form a precedent for other like cases; at other times they were special, particular or individual, (personales,) and not intended to form a precedent. The emperor had this power of Irresponsible enactment by virtue of a certain lex regia, whereby he was made the fountain of justice and of mercy. Brown. Constitutiones tempore posteriores po-tiores sunt his quae ipsas praecesserunt. Dig. 1, 4, 4. Later laws prevall over those which preceded them.
-- Black's Law Dictionary
Legal Definition
Laws of the Roman emperors.
-- Ballentine's Law Dictionary