The Parliament of Catalonia (left image) is likely to pass tomorrow a declaration on the sovereignty of the Catalan people. This will be a milestone text in the history of the country, given that for the first time since autonomy was restored, Catalonia could be defined as a "sovereign political and legal subject", if the proposal by three parties CiU, ERC and ICV is taken forward.

A declaration of sovereignty does not necessarily mean that independence is going to follow suit. Sometimes it is used as a preliminary legal text where the reasons for self-determination are put forward, and later on (maybe years) a declaration on independence follows. On other occasions, the process does not lead to the establishment of an independent state, but to a new agreement between the self-declared sovereign territory and the state.

Within the same state, two parallel but very different processes

The dissolution of the Soviet Union gives examples of both cases. The Estonian Soviet Socialist Republic issued a declaration of sovereignty in 1988, shortly before the USSR collapsed. Estonian deputies then agreed that the laws of Estonia were to prevail over those passed by the Soviet Union itself. Indeed, the Estonian Parliament started to pass laws that superseded those of the USSR, and finally it declared full independence in 1991 after the holding of a referendum.

Independence, on the contrary, was not the outcome of the declaration of sovereignty that was passed by the Turkic-speaking Tatarstan in 1990. The republic, a member of the then Russian Soviet Federative Socialist Republic, proclaimed "Tatar state sovereignty", but the text also said that the declaration was thought "for the collaboration of the Tatar SSR in the creation and signing the Union Treaty, for agreements with the Russian Federation and other republics". The final result of this process was a deal between Moscow and Kazan in 1994: Tatarstan accepted to remain as a part of the Russian Federation and included clear limits to its own sovereignty in Article 1 of its Constitution.

The Soviet examples are very relevant for the Catalan issue. In both cases, the original declaration had clearly different goals. In the Estonian case, it was the prevalence of Estonian laws and the "restoration", as it was said, of national independence; in Tatarstan, the scope always included remaining within Russia. The proposal by CiU, ERC and ICV foresees "dialogue and negotiation" with Spain and European and international institutions, but it also underlines a fundamental principle: the democratic legitimacy of the process and the fact that it reflects popular will. This principle was not central in the Estonian and Tatar declarations.

Quebec: a referendum before declaring sovereignty

Possibly even more than former Soviet republics, Quebec has traditionally been perceived as a lighthouse for Catalan sovereignists. It is interesting to see that Quebecers decided in 1995 to proceed in a reverse way if compared to Catalonia. First of all, the government of Quebec called a referendum, in which it was asked to citizens if the country "should become sovereign after having made a formal offer to Canada for a new economic and political partnership". The government plan was to have the referendum won, and only after to pass an act declaring Quebec "a sovereign country". Since Quebecers voted against, albeit by a narrow margin, the plan was aborted.

These are only three concrete cases where procedures and outcomes were clearly different. The last three decades of world history are full of examples of other processes that had even more different results. Some of them have created de facto independent but unrecognized states (such as the Declaration of Burao of 1991, where clan elders asserted sovereignty of Somaliland), while others have had little, if any, immediate effect, such as the Inuit declaration of 2009, a text that acknowledges that "old ideas of sovereignty are breaking down" and that "sovereignties overlap".