In the subsequent decade, several bilateral and multilateral treaties and agreements regulating relations were entered into: This Convention for the Definition of Aggression, an initiative of the Soviet Government, defined in Article 2 various acts as aggression, including naval blockades.
The Convention also stipulates that "No political, military, economic or other consideration may serve as an excuse or justification for the aggression referred to in Article 2." Estonia adopted the Estonian Declaration of Independence on 24 February 1918.
while under Soviet rule and German occupation from 1940 to 1991.
The prevailing opinion accepts the Baltic thesis of illegal occupation and the actions of the USSR are regarded as contrary to international law in general and to the bilateral treaties between the USSR and the Baltic states in particular.
On one hand, legal recognition of Baltic incorporation on the part of other sovereign nations outside the Soviet bloc was largely withheld based on the fundamental legal principle of ex injuria jus non oritur, since the annexation of the Baltic states was held to be illegal.
The four countries on the Baltic Sea that were formerly parts of the Russian Empire – Finland, Estonia, Latvia and Lithuania – consolidated their borders and independence after the Estonian, Latvian and Lithuanian independence wars following the end of World War I by 1920 (see Treaty of Tartu, Latvian-Soviet Riga Peace Treaty and Soviet-Lithuanian Treaty of 1920).
The European Great Powers accorded de jure recognition of Estonia and Latvia on January 26, 1921 and Lithuania on December 20, 1922.
The United States extended de jure recognition to all three states on July 28, 1922.
This principle self-determination reflected one of four key principles proclaimed by Lenin and Stalin on November 15, 1917 in the Declaration of the Soviet Government: "The right for Russia's peoples of free self-determination even unto separation and establishment of independent states." With the creation of the Union of Soviet Socialist Republics on July 6, 1923, the new union had adopted all treaties entered into previously by Soviet Russia and the original peace treaties continued to be a basis for relations between the USSR and the respective Baltic states.
the resistance by the Baltic people to the Soviet regime, and the uninterrupted functioning of rudimentary state organs in exile support the legal position that sovereign title never passed to the Soviet Union, which implied that occupation sui generis (Annexionsbesetzung or "annexation occupation") lasted until re-independence in 1991.
They have also argued that in accordance to the internal Soviet laws and constitution, restoration of independence was illegal and the Baltic republics could only become newly created sovereign entities via the secession laws of the USSR.
The document stated a number of principles such as freedom of expression, religion, assembly and association.
These principles were further elaborated in the Provisional Constitution of 1919 and the first Constitution of 1920.Popular sovereignty was to be the basis of Estonia.