ICG (International Crisis Group) or ICJ (International Court of Justice) ?
I think you meant ICJ but still I can't figure out what are the special cases you are referring to !
The CSS International Law exam (to the best of my knowledge) requires you to know some of the most famous cases decided by the ICJ and it's a very good value-addition to go through the latest decided cases, you can get them at the ICJ website
International Court of Justice
http://www.icj-cij.org/homepage/index.php?lang=en