He was arrested there under the federal Fugitive Slave Law on April 4, 1851. Following a dramatic court trial, he was returned to his owner against the strong protests of abolitionists. The federal government sent U.S. Marines to march Sims down the streets of Boston, to be taken away on a warship and transferred back to Georgia. Sims was sold to a new owner in Mississippi, but escaped in 1863 and returned to Boston.
The "Sims Tragedy" was a cause célèbre in the Massachusetts abolitionist movement (see for instance, the references in Henry David Thoreau’s Slavery in Massachusetts) and drew sympathy from many northerners. Probably the most renowned fugitive slave case of the decade also occurred in Boston. Three years after Sims' arrest, Judge Edward G. Loring ordered the fugitive Anthony Burns back into slavery in Virginia. Another attempt was made by abolitionists as hundreds of whom poured onto the streets on various occasions in support of the fugitive. As in the case of Sims, Burns was also taken by U.S. Marines to a ship destined for Virginia, but by the time of Burns's deportation his cause had become so celebrated that 50,000 people watched federal officers take to the wharf. Within a year, Burns was back in Boston. African Americans had raised $1,300 to pay the price being asked for him.