Italy’s instrument of ratif was deposited on July 26, 1999…Italian choice to proceed first with the ratif and to tackle only later the considerable problems of adapting the domestic legal system to the RS undoubtedly had also influenced a number of other states in taking the same approach. Experts have often referred to the Italian procedure as a useful model for states that have that have to spend considerable time to adapt their particularly complex domestic legislation to the Statute. [215-6]
When enacting the law authorizing the President of the Republic to ratify a convention and issuing the execution order, any constitutional issues should have been considered by the Parliament prior to approving the authorization law. Obviously, this does not preclude the Parliament from reconsidering any constitutional issues of a ratified treaty when adopting the implementing legislation. This may change if the subsequently convened Parliament has a political majority different from the one which adopted the ratif law. If in such a situation a Parliament concludes that a ratified treaty is in violation of the Constitution, it should either trigger a constitutional review or proceed by means of withdrawal from the treaty. According to Italian legal system, any constitutional check on laws already entered into force is reserved to the Constitutional Court, which has the power of nullifying and law due to constitutional flaws. [220-1]
Italy chose to ratify the Statute first and then to deal with the implementation later. The choice was facilitated by the privileged position that the Italian Constitution grants to international treaty and customary law, mainly through the combination of the mechanism provided for under articles 10 and 11 of the Constitution. 
The ratif process of some treaties have been delayed or, due to the time elapsed, participation in the treaty is missed (1906 the Hague Convention of 1968 Convention on non-applicability of statute of limitations). Some of the ratified treaties have not yet, or not at all, been fully implemented (e.g. 1980 Geneva Convention on Certain Conventional Weapons and the Protocols thereto). There are also cases where the implementing legislation preceded the entry into force of the treaty provision (e.g for the 1997 Ottawa Convention on anti-personnel mines) or even went beyond the obligations imposed by the treaties (eg for the Hague Convention of 1899 and for the 1948 Genocide Convention) [222-3]
An extensive analysis of existing national laws leads readily to the conclusion that legislative measures are needed mainly for the implementation of crimes against humanity; to a minor extent, implementation for war crimes, and only a minimum is needed to amend the crime of genocide (ie. As to the age of minors, to be raised from 14 to 18 years to relflect the Element of Crimes under article 6(e))…the Italian procedure for the ratif of the RS allowed for delaying the consideration of most of the problems related to implementation, but required the Parliament to go through a first reading of the Statute in the light of the Italian Constitution.