Scotland has a parliament and its own identity unique from the United Kingdom. Nevertheless, it is still part of the United Kingdom and is not a sovereign state. Last year, the pro-independence Scottish National Party (SNP) won the election in Scotland. However, only 1/3 of Scots support independence from the UK. A major concern for Scots regarding independence is whether or not Scotland would have to reapply to be a member of the European Union. Currently, Scotland is a member of the EU as part of the United Kingdom. Some Scots are concerned that they would end up at the back of the line for entrance, behind Albania and Macedonia.
A possible comparison to Scotland is that of the independence of the Balkan States from Yugoslavia. After Serbia and Macedonia declared their independence, Spain refused to recognize their independence, and attempted to prevent their entrance to the European Union. Spain was concerned about possible secessionist movements in their territory. Thus, there is the concern of how an independent Scotland will be perceived.
Lastly, the United Kingdom would likely not award Scotland independence so quickly. One key point of dispute is the question of oil rights in the North Sea. Ninety-five percent of the oil is on the Scottish side of the border. However, the United Kingdom could dispute the border between Scotland and the United Kingdom. While a lack of public support makes an independence campaign unlikely, it is a possibility and there a number of likely disputes.
The question of Scottish independence, however (un)likely, is interesting because it does not fit within the classical self-determination model, like the former Yugoslavia. Under customary international law, self-determination is limited by the principle of uti posseditis and usually applied to classical colonial entities. Both the UN Declaration on Principles of International Law and the 1993 Vienna Declaration affirm the right of self-determination to peoples under colonial domination or foreign occupation but reject secession from independent states that, in essence, exhibit good governance. Scotland is not a (former) colony, but its own country but part of the United Kingdom.
Self-determination has been undergoing an expansion in an attempt to recognize and deal with such non-classical movements like the South Sudanese secession from Sudan. The International Court of Justice’s Kosovo advisory opinion articulated this shift as recognizing the independence of “peoples of non-self-governing territories and peoples subject to alien subjugation, domination, and exploitation.” Again, however, Scotland does not exactly seem to fit the bill. If Scotland does manage to “secede” (if it may be called as such), it will add to the rapid expansion of classical self-determination law.