This article analyses classic issues of public international law on the recent example of Crimea's unification with the Russian Federation. Legal claims of both sides involved in this territorial contention have been scrutinized, in particular whether Crimeans are entitled to external self-determination or the principle of sovereignty and territorial integrity of Ukraine should prevail. In addition, this article argues that the self-determination right is subjected to certain limitations, which ex lege exclude its legality. Such would be the Russian military intervention, which is hardly justifiable in terms of exceptions accepted by customary international law (intervention by invitation, protection of own citizens abroad). One would rightly ask why the Russian minority in Ukraine is devoid of independence taking into account the partially successful secession of Kosovo, where ethnic Albanians achieved statehood in the aftermath of the 1999 NATO military intervention. The two wrongs by no means create a right, but a deeper insight into the different treatment in similar situations could not go without attention in this article. In conclusion, the deliberations over the potential future of Crimea are put forward, where again the unresolved problem of facts confronting the legality returns, which in this case is additionally augmented by the involvement of the global Great Power and permanent member of the UNSC, the Russian Federation, in the contention.