And Lincoln said that if you believe in the Fugitive Slave Act being required by Article IV, you must also believe that the protection of the slave owner and the territories deserves federal protection; the two arguments were perfectly parallel. Douglas said it didn't matter how the Supreme Court in the abstract decided the question of slavery in the territories; if the slave owner went to the territory, he had to get local regulations to protect his property.

The Real Abraham Lincoln: A Debate (2002)