On September 2, 1991, a joint session of the People’s Deputies of the Nagorno Karabakh Autonomous Region and Shahumian regional councils, declared the establishment of the Nagorno Karabakh Republic (NKR), which was followed by a referendum.
According to Article 3 of the “Law on Procedure for Resolving Questions Connected with a Union Republic’s Secession from the USSR” (Supreme Council of the USSR April 3, 1990 N 1409-I):
In a Union republic which includes within its structure autonomous republics, autonomous oblasts, or autonomous okrugs, the referendum is held separately for each autonomous formation. The people of autonomous republics and autonomous formations retain the right to decide independently the question of remaining within the USSR or within the seceding Union republic, and also to raise the question of their own state-legal status.
(Chapter 11. Autonomous Oblasts (Region) and Autonomous Okrug (CONSTITUTION OF THE UNION OF SOVIET SOCIALIST REPUBLIC, 1977) Article 86. An Autonomous Oblast is a constituent part of a Union Republic or Territory. Article 87. …. The Azerbaijan Soviet Socialist Republic includes the Nagorno-Karabakh Autonomous Oblast.)
Based on this law the referendum was held on December 10, 1991.
• The percentage of voters was 82.2 percent of the total number of voters; • The question posed: “Do you agree that the proclaimed Nagorno Karabakh Republic be a sovereign state, independently determining the forms of its cooperation with other states and communities?” • 99,9 percent of the voters answered “Yes” The referendum was monitored by more than 40 international observers.
On 18 October 1991, the Supreme Council of Azerbaijan adopted a Declaration of Independence which was affirmed by a nationwide referendum on December 25, 1991.