Answer:
slavery might become legal everywhere.
Step-by-step explanation:
Following the Supreme Court verdict on Dred Scott v. John F.A. Sandford, in 1857, where it was decided 7 - 2 in favor of Stanford that the Missouri Compromise of 1820 was unconstitutional.
Many people in the north felt or believed that given that the Supreme Court had ruled that Congress did not have the right to ban slavery, "slavery might become legal everywhere."