What did northerners dislike about the fugitive slave law of 1850?
Northerners, especially abolitionists, disliked the 'Bloodhound Law' as it required escaped slaves to be returned to their masters even if they were found in a free state. Northerners worried that the Fugitive Slave Act of 1850 was part of a vast conspiracy of the southern plantation elite.
Northerners were not at all happy about the Fugitive Slave Law of 1850. The law forced federal marshals to assist slave hunters in the pursuit and apprehension of runaway slaves. If they refused, they could face fines. In addition, these marshals had the power to deputize regular citizens and force them to assist as well. The act, in essence, forced people who were vehemently against slavery to participate in it.
What part of the compromise of 1850 pleased Northerners the most and which part pleased Southerners the most?
The first U.S. Fugitive Slave Law was passed in 1793, but the more infamous act was the updating and strengthening of this law in the "Fugitive Slave Act of 1850"-- one of a set of five bills known collectively as the "Compromise of 1850". The last such law passed in 1850 (replacing earlier forms going back to the 1790s), as one of five pieces of legislation known collectively as "the Compromise of 1850".