How can you tell that Anthony Burns was a slave?

Anthony Burns was identified as a slave through his legal status and the circumstances surrounding his capture. He was born into slavery in Virginia and escaped to Boston, where he was later apprehended under the Fugitive Slave Act of 1850. The public outcry and the legal proceedings that followed highlighted his status as a slave and the broader implications of slavery in America. His case became a significant event in the abolitionist movement, emphasizing the brutal realities of slavery and the struggle for freedom.