At the 7th (Special) Session of the Supreme Soviet of the Soviet Union Ninth Convocation on October 7, 1977, the third and last Soviet Constitution, also known as the Brezhnev Constitution, was unanimously adopted. The official name of the Constitution was "Constitution (Fundamental Law) of the Union of Soviet Socialist Republics" (Russian: Конститу́ция (Основно́й Зако́н) Сою́за Сове́тских Социалисти́ческих Респу́блик).
The preamble stated that "the aims of the dictatorship of the proletariat having been fulfilled, the Soviet state has become the state of the whole people." Compared with previous constitutions, the Brezhnev Constitution extended the bounds of constitutional regulation of society. The first chapter defined the leading role of the Communist Party of the Soviet Union (CPSU) and established principles for the management of the state and the government. Articles related 1 defined the USSR as a socialist state, as did all previous constitutions:
The Union of Soviet Socialist Republics is a socialist state of the whole people, expressing the will and interests of the workers, peasants, and intelligentsia, the working people of all the nations and nationalities of the country.
The difference is that, according to the new Constitution, the government no longer represented the workers and peasants alone. Later chapters established principles for economic management and cultural relations.
The 1977 Constitution was long and detailed. It included twenty-eight more articles than the 1936 Soviet Constitution. The Constitution explicitly defined the division of responsibilities between the central and republic governments. For example, the Constitution placed the regulation of boundaries and administrative divisions within the jurisdiction of the republics. However, provisions established the rules under which the republics could make such changes.