August 24, 1991 Ukraine declared its independence (as long as it was part of the Ukrainian Soviet Socialist Republic in the USSR).
Declaration of Independence of Ukraine on August 24, 1991 was adopted on December 1 1991 by popular vote. Public holiday, this event was only in June 1992, when the Supreme Council decided to consider August 24 Independence Day of Ukraine.
In fact, the first Independence Day was celebrated on July 16, 1991-th - in memory of the fact that on July 16, 1990 the Supreme Soviet of the Ukrainian SSR adopted the Declaration of State Sovereignty of Ukraine.
The first Constitution of the independent Ukrainian state was adopted by the Verkhovna Rada of June 28, 1996. Article 1 of the Constitution states: "Ukraine - a sovereign, independent, democratic, social state of law".