With admirable integrity and consistency, Spooner criticized both the Civil War and reconstruction, unlike most of his abolitionist colleagues who opportunistically supported the war. He saw both anti-slavery and pro-secessionism as based on the same principle - sovereignty of the individual. He was a scathing abolitionist critic of the Republican party.

The man, who, like the Republican party, consents to the existence of slavery, so long as the slaves are but kept out of his sight, is at heart a tyrant and a brute. And if, at the same time, like the more conspicuous members of that party, he makes loud professions of devotion to liberty and humanity, he thereby just as loudly proclaims himself a hypocrite. And those Republican politicians, who, instead of insisting upon the liberation of the slaves, maintain, under the name of State Rights, the inviolability of the slaveholder’s right of property in his slaves, in the States, and yet claim to be friends of liberty, because they cry, "Keep the slaves where they are;" "No removal of them into the Territories;" "Bring them not into our neighborhood," - are either smitten with stupidity, as with a disease, or, what is more probable, are nothing else than selfish, cowardly, hypocritical, and unprincipled men, who, for the sake of gaining or retaining power, are simply making a useless noise about nothing, with the purpose of diverting men's minds from the true issue, and of thus postponing the inevitable contest, which every honest and brave man ought to be ready and eager to meet at once. - Lysander Spooner, Address of the Free Constitutionalists to the People of the United States (1860).