You can find further details here: http://lawcomic.net/guide/?p=864
It's written by an actual lawyer, in spite of being in comic format.
You run a business in the 1800s that frees blacks from the South and transports them to the North. If caught, you risk some severe penalties, maybe even death.
Someone finds out and blackmails you. What do you do?
EDIT: Also, in your example, this was eventually fixed by changing the law, not by breaking it. And, to the best of my knowledge, everyone ran the underground railroad for free, not for profit.