The Fugitive Slave Act of 1850 and Its Implications for Current Controversies
Background here for those of you who were stoned in high-school history classes.
The use of nullification (a declaration that state and local governments will not assist the Federal government to enforce some laws) by slave states has given nullification a bad name. On the contrary, nullification was also used by the free states of Wisconsin and Vermont to hinder enforcement of the Fugitive Slave Act.
The use or endorsement of nullification by liberals or libertarians (with respect to immigration law, for example) is not necessarily hypocritical.
We Won't Let You Stay Uninvolved
In the early stages, one common excuse given by supporters of shady activities (sometimes those activities have real victims and sometimes they don't) is: “If you don't like it, don't do it.” This is followed by “We won't let you stay uninvolved.” This happened in the case of slavery (the Fugitive Slave Act), the case of of selling possible abortifacients (the Affordable Care Act), and in the case of gay marriage.
Shooting the Wounded
Slavery was legal in much of the U.S. The Fugitive Slave Act was a matter of starting to eliminate the resistance. You can think of it as “shooting the wounded.”
The Confederate Flag
One excuse for flying the Confederate flag is that it's a symbol of resisting centralization. On the other hand, when it comes to centralization, Dixie fired the first shot.