How did the Dred Scott and fugitive slave law support slavery?

The Fugitive Slave Act was a crackdown on runaways. It was the only gesture that Congress could make to the South, as it was now almost impossible to create new slave-states.

The Dred Scott decision was a shock judgment by the Supreme Court that slavery was protected by the Constitution. It swung on the definition of property. When the Founding Fathers declared that a man's property was sacred, they would have included slaves in their definition of property. So the Court argued that slavery must be legal in every state of the Union.