Why did southerners believe they had a right to leave the union during the civil war?

Southerners believed they had a right to leave the Union based on the principle of states' rights, arguing that the Constitution granted states the authority to secede from the federal government. They felt that their way of life, particularly the institution of slavery, was threatened by the increasing power of the federal government and the election of anti-slavery leaders. Many southerners viewed secession as a necessary measure to protect their economic interests and social order, which they believed were under attack. Additionally, the belief in a distinct Southern identity contributed to their justification for leaving the Union.