Delancyplace.com published this article on 12/28/2015. It relates directly to the story of Butler and is an interesting read.
“The Congress of the United States — the very Congress created by the wonderful and epoch-making Constitution of the United States — is nevertheless capable of creating truly horrendous laws. The most oppressive law in United States history was arguably the Fugitive Slave Act of 1850, crafted by Henry Clay as a compromise between North and South when it was in fact a capitulation to the South, it was marshaled through Congress by Senator Stephen Douglas, and was vigorously enforced by Millard Fillmore, the president many regard as the worst in our history. It led directly to the demise of the American Whig party and the first shots of the American Civil War:
The Fugitive Slave Act of 1850 was one of the most repressive and unfair statutes ever adopted by the United States. It was also a law that created, for the first time, a national system of law enforcement. In the wake of Prigg v. Pennsylvania, state officials throughout the North had refused to enforce the Fugitive Slave Act of 1793, and a number of states passed legislation prohibiting their judges from hearing fugitive slave cases and prohibiting federal officials or private slave catchers from using state jails to secure alleged fugitive slaves. Southerners complained, with some legitimacy, that these new personal liberty laws made it impossible for them to exercise their constitutional right to recover fugitive slaves. …”