Different Notions of this international law Concept - or simply Double Standards?
We have also seen the different reactions from western governments (who outweigh the international community when it comes to international law): While actively supporting the struggle of e.g. South Sudan, Kosovo, Kurdistan or the Tibetian's call for self-determination, they fiercly oppose the struggle of Eastern Ukrainians to seperate from Ukraine or of Palestinian self-determination. Other examples of "bad" self-determination are Indian occupied Kashmir or the Turkish Republic of Northern Cyprus.
Currently, western governments are keen to create a new state of Kurdistan, and to split Iraq into smaller entities. Independent Kurdistan is now going to be pushed for by Europe and the US who are eager to deploy arms, give logistic and economic support and on a diplomatic level already recognize Kurdish representatives. In utter disregard for Iraqi sovereignty and territorial integrity, the US and the EU make every effort to help this independent Kurdistan to gain territory from Iraq (and probably even Turkey and Iran) with bombs, arms, weapons and money.
Western governments tidily differentiate between "good" and "bad" occupation, between "good" and "bad" self-determination. However, the law ought to be blind. Under international law, self-determination is an absolute right, considered to be ius cogens, irrespective of the respective peoples' convictions and creed. And occupation remains illegal, no matter, what the (geo)political interests are.
Let us recall the European Union's reaction to the independence referendum of Crimeans in March this year:
"The solution to the crisis in Ukraine must be based on the territorial integrity, sovereignty and independence of Ukraine, in the framework of the Ukrainian Constitution as well as the strict adherence to international standards. [...]
We reiterate the strong condemnation of the unprovoked violation of Ukraine's sovereignty and territorial integrity and call on Russia to withdraw its armed forces" 
Why not adopt this same stance on the current situation in Iraq?
 Council of Europe, Joint Statement on Crimea, Brussels, 16 March 2014 EUCO 58/14 PRESSE 140 PR PCE 53