"Between 1800 and 1830, slave states began restricting manumission, seeing free blacks as potential fomenters of slave rebellion. Now you could buy your friends, but you couldn’t free them unless they left the state – which for the freed slave could mean leaving behind family still in bondage. So more free blacks took to owning slaves benevolently. Being a nominal slave was risky – among other things, you could be seized as payment for your nominal owner’s debts. But at least one state, South Carolina, granted nominal slaves certain rights, including the right to buy slaves of their own."