Who stood up for the rights of slaves over power of the federal government?

Frederick Douglass was a prominent advocate for the rights of enslaved individuals, often challenging the power of the federal government to uphold slavery. As a former enslaved person and a powerful orator, he used his platform to demand equality and justice, emphasizing that true liberty could not coexist with the institution of slavery. Douglass argued for the necessity of abolition and the recognition of African Americans as full citizens, directly opposing government policies that perpetuated slavery.