The issue of states' rights was one of the main causes of the onset of the Civil War. The Southern states believed that they had the right to secede from the Union if they felt that their states' rights were being violated. The Northern states, on the other hand, believed that the Union was a perpetual entity that no state could secede from. This disagreement over the interpretation of the U.S. Constitution led to the secession of the Southern states and the eventual outbreak of the Civil War. Therefore, the best answer to your question would be that the issue of states' rights was one of the main causes of the onset of the Civil War.
