Conservative and former diplomat Alan Lee Keyes believes that a Supreme Court ruling striking down restrictive state marriage bans will lead to the “dissolution of the United States.”

Keyes, whose daughter is gay, issued his warning in a lengthy op-ed.

The high court has agreed to review cases challenging bans in four states. Oral arguments will be heard in April and a ruling is expected by June.

According to Keyes, a decision favoring marriage equality “could very well be as momentous as the Dred Scott decision in the 19th century, and just as fraught with potential fatal implications for the future Liberty and Union of the United States.”

Such a ruling would lead to civil war, Keyes concludes.

“This would be an attack on the people of the United States more grievous than that which led the first generation of Americans to declare their independence from Great Britain,” he wrote. “If even a significant minority of Americans continue in their attachment to the unalienable right of liberty (as opposed to the licentious freedom that has, in some quarters usurped that name) this attack is likely to produce the separation and dissolution of the United States, for like humanity itself the United States is inconceivable apart from respect for God-endowed unalienable right.”