I believe there is a higher law than the Constitution.
He picked up a copy of the Fugitive Slave Act, set fire to it, and said in the language of the Bible, "and let the people say Amen." The vast crowd responded, "Amen!" He picked up a copy of the decision which had sent Burns back to bondage, and copy of a charge to the jury which had tried Burns's erstwhile rescuers. He burned these, too, and asked the crowd to cry "Amen"; it did so eagerly.Then he reached for a copy of the Constitution, held it in his hand and declared that it was the "parent of all the other atrocities." "A covenant with death," he called it, "An agreement with Hell." He set it afire and cried out as it burned, "So perish all compromises with tyranny!" 'And let the people say Amen.'" A huge should of "Amen" echoed. But this time hisses and angry outcries were also audible.
The changed reaction of the crowd probably reflected more general dismay at such abuse of a treasured national symbol than disagreement with Garrison's constititional views.
Philip S. Paludan, A Covenant With Death, 1975, p. 3