Complex sentence: The constitution established the republic's status and authority within Russia and replaced the previous Constitution of the Autonomous Republic of Crimea that was repealed by referendum during the 2014 Crimean crisis.
Split into simpler sentences: The constitution established the republic's status and authority within Russia. It is supposed to replace the Constitution of the Autonomous Republic of Crimea, claiming that it was repealed by referendum during the 2014 Crimean crisis.