What did many people in the North believe after the Supreme Court's ruling in the Scott v. Sandford case?

The Dred Scott decision served as an eye-opener to Northerners who believed that slavery was tolerable as long as it stayed in the South. If the decision took away any power Congress once had to regulate slavery in new territories, these once-skeptics reasoned, slavery could quickly expand into much of the western United States. And once slavery expanded into the territories, it could spread quickly into the once-free states.