"The view that Roger promulgated his legislation ― often called by historians the Constitutiones of Ariano ― in this assembly is merely a hypothesis.  It seems rather unlikely that the king would choose such an insignificant place as Ariano from which to promulgate a body of legislation applying to the whole kingdom.  The one thing that is certain is that once his kingdom was consolidated Roger issued a series of laws.  What we do not know is when and where he did this."

Hubert Houben, RogerII. von Sizilien: Herrscher zwischen Orient un Okzident (Darmstadt: 1997), translated into English Roger II of Sicily: A Ruler between East and West  (Cambridge Medieval Textbooks; Cambridge:  2002) 136

"The fact that kings published laws does not make it more likely that they issued a 'code', texts of which were somehow preserved in the Vatican and Cassino manuscripts." 

David Matthew, The Norman Kingdom of Sicily (Cambridge-New York: 1992) 187