"Moderate abolitionism," though it's a phrase that could be used in a study of abolitionist ideologies, doesn't make much sense when used to describe the span of social opinion overall. "Abolitionists," those people committed to the direct and entire abolition of slavery and equality for the freedmen, hostile to the US Constitution because of its compromise with the "Slave Power," were extreme persons in 1850, though they may have comprised the plurality of opinion in some parts of New England. You might have said that recaption and rendition were part of the process that radicalized moderate anti-slavery opinion.

The idea, however, that the radicalizing effect of the Second Fugitive Slave Act lay in forcing the cooperation of local authorities is ahistorical. The First Fugitive Slave Act, of 1793, required more local cooperation than the Second, which created federal commissioners to hear and determine issues of status and rendition. The creation of federal commissioners resulted specifically from the refusal of state officials to perform their roles. The statute's effect was to create a biased federal administrative judiciary (which was paid more for rendering a slave than for finding that the person sought was not a fugitive from servitude) in order to avoid reliance on increasingly antislavery judges.

An ugly neologism, created after 1950, when the world had apparently lost all knowledge of Greek. Why use it?

Hardly an example one would want to have to emulate, in view of the deterioration of the Union. From a historical point of view, you should have pointed out, this was merely an intensification of the confrontation between antislavery state governments and the imperial federation that led to state anti-kidnapping enforcement against recaption, thus to Prigg v. Pennsylvania, to resistance to the First Fugitive Act, to the Compromise of 1850, and (after the personal liberty laws began to produce violent resistance to federal rendition) to Ableman v. Booth and eventually the dissolution of the Union.

In an ideal world, state legislatures would pass similar personal freedom laws and local agencies would refuse to help ICE. It would also help if more Americans started organizing and making modern versions of the poster you saw earlier.

But of course, that's not what's going to happen. Cities in which immigrants and the children of immigrants have been the bones of the political system for generations will continue to refuse assistance and to render as much equality of service to undocumented persons as they can. In white suburbs, along the southern border, and in communities heavily suffering from unemployment in hard economic times, "illegal aliens" are the consensus target of white supremacy and other nativisms, pro-worker populism, and the rage of taxpayers paying high property taxes on underwater properties, who believe that undocumented persons expensively overuse public services without paying for them. Too many votes exist in those places for the Republican Party to ignore, and the "national security" hysteria it continues to employ as a weapon against the left and the Democratic Party, and in support of law enforcement and other uses of public force, too closely predisposes it towards a para-military view of immigration matters for there to emerge in the near- or medium-term any workable legislative solutions. George W Bush showed the impossibility of undertaking any significant movement when he was the Republican President with a Republican Congress; Obama has indicated that he will now try, in the aftermath of his current legislative victory, but he will not be able to hold the Democratic Congressional party together on this as he did on health care, and he will get no Republican support.

Pressure to moderate the system will be exerted by one branch of elite opinion (like the owners of the New York Times, or the members of National Public Radio), while fulmination against "illegals" will occur in the opinion-control systems of the right, meant to play to a substantially larger if less "influential" audience. Where this essay could usefully be revised, I think, is to substitute for the politics of the 1850s (which even if accurately rendered are not really relevant) a more direct analysis of the political possibilities in the present situation.