I have found this. From a Princeton law site.
"The principle of territorial integrity or political unity would seem to be superior to that of self-determination, since "[n]othing in the foregoing paragraphs" shall be construed to authorize or encourage "any action" which would impair this principle. However, this restriction applies only to those states which conduct themselves "in compliance with the principle of equal rights and self-determination of peoples as described above and thus possessed of a government representing the whole people belonging to the territory without distinction as to race, creed or colour." (emphasis added) The requirement of representativeness suggests internal democracy, but it cannot mean that the only government that can be deemed "representative" is one which specifically recognizes all of the various ethnic, religious, linguistic, and other communities within a state. A more persuasive interpretation, which would be consistent with the concerns of most UN member states when the declaration was adopted in 1970, is that a state will not be considered to be representative if it formally excludes a particular group from participation in the political process, based on that group's race, creed, or color; the paradigm at the time was apartheid in South Africa, which was a major international concern until the transition to majority rule in the mid-1990s. The mere fact that a democratic, non-discriminatory voting system results in the domination of political life by an ethnic majority in a particular state does not necessarily mean that the state is unrepresentative within the terms of the Declaration on Friendly Relations, although it may violate subsequent norms of minority rights that have been proclaimed, beginning in the 1990s."
So in international law it looks like Scotland does not have a right to self determination. This is of course different from the political reality. Arguably by allowing one referendum a precedent has been set.