The War of Laws (Russian: Война законов, Voyna zakonov) was the series of conflicts between the central government of the Soviet Union and the governments of the Soviet republics during the so-called "parade of sovereignties" in the last years of the Soviet Union (1989–1991), which eventually contributed to the dissolution of the Soviet Union. When Soviet General Secretary Mikhail Gorbachev and the Communist Party of the Soviet Union decided to formally release their control of the republics, the individual governments began to reassert their own sovereignty and dominance in their respective areas. That included making their own laws separate from those of the Soviet central government and refusing to pay taxes. These events worsened the Soviet Union's economic disintegration and were a major factor in its 1991 collapse.

In 1989–1991 legislative gridlock developed between the Soviet government and the Soviet republics. Many laws were passed by the republics' governments which gave them jurisdiction over their own territory and were overturned by Moscow as unconstitutional. In response, the republics officially stated that Moscow's rulings were not relevant to the matter over which the original law had been passed. That led to a constant conflict over constitutional wording and whether the republics or Moscow were supreme.

The republics began to assert their sovereignty over their regions: the first was Estonia in 1988, and the 14 others had followed by 1990. Native languages were readopted, instead of Russian. That alienated some large cities made up of Russian citizens, which led to attempts to create or recreate even smaller republics. The new governments continued the war of laws by rejecting new laws passed by Moscow and by creating their own. While sometimes the laws passed by the republics were contradictory, they were largely almost identical to those being passed in Moscow and formed a system of what was termed "parallel power".

For instance, Tatarstan, with a plurality population of Muslim Tatars, declared itself an independent state with the right to self-determination in 1990 and claimed ownership of its massive oil reserves. It set itself free of Russian law and Russian taxes, as did many of Russia's 89 regions.

There was a length war of laws between the Georgian SSR and the Central Soviet government due to the status of the South Ossetian Autonomous Oblast when the Oblast requested elevation to an Autonomous Soviet Socialist Republic on November 10, 1989. A legal solution could not be found, and the conflict spiraled into the South Ossetian War, one of the ongoing frozen conflicts.

As the splits became more and more pronounced, the Soviet government began speaking of returning to the status quo by means that would not have been considered earlier. Gorbachev responded to this by putting marketization and constitutional amendments on hold in order to focus on reorganizing the Soviet Union to maintain its unity. The New Union Treaty was made to give more control to the republics over their own affairs, an attempt to keep them in the Union. However, the act was far too late, and no amount of publicizing made the republics change their minds from withdrawal.

The vacuum of power that had been created was filled with the arrival of Boris Yeltsin, who attempted to gain support for himself and denounced Gorbachev. The Kremlin and Gorbachev responded with a censure of Yeltsin and his remarks.

The anti-government feelings were influenced further by the August Coup, which involved the attempted overthrow of Gorbachev. It was put down, but the destabilization reduced Gorbachev's power drastically. Control of the situation moved toward the republics, and Lithuania, Latvia and Estonia were given independence. The 12 other republics settled on much less strict forms of Soviet governance. The Soviet Union was declared to have ended officially with the signing of the Belavezha Accords between Russia, Ukraine and Belarus.