The Dred Scott decision, delivered by the Supreme Court in 1857, infuriated many Northerners for several key reasons. First and foremost, the ruling essentially affirmed the idea that enslaved individuals were not citizens and had no legal grounds to seek freedom through the courts. This struck at the heart of the growing abolitionist sentiment in the North, where many were advocating for the rights of all individuals, regardless of their race.
Additionally, the decision declared that Congress had no authority to regulate slavery in the territories, which undermined the Compromise of 1850 and the Missouri Compromise. It meant that slavery could potentially spread into areas where it had been previously restricted, which alarmed those who were pushing for the expansion of free states and the limitation of slaveholding territories.
Northerners saw the ruling as a direct threat to their values and way of life. It intensified the already growing divide between the North and South and galvanized anti-slavery activists. The belief that a judicial ruling could deny the humanity and rights of an individual was deeply alarming and contributed to the rise of a more vigorous abolitionist movement in the North.