Following Denmark Vesey's arrest and trial, the South Carolina legislature amended the Negro Seaman's Act of 1820 to remove the exception for "free negro or mulatto seamen" from being temporarily arrested and imprisoned while their ship ported. Johnson feared that the case would lead to creditor-ship owners leaving free seamen in jails to avoid paying wages as well as lead to other bans based on racial classification. In the case of "Elkison v. Deliesseline" (1822), Johnson, presiding over his duties on the Circuit Court for the District of South Carolina, found that "the transfer of commerce and treaty powers to the national government eliminated state authority to enact conflicting legislation" and therefore invalidated the statute. It was the first time since 1789 that a federal court invalidated state legislation because of its conflict with the Commerce Clause. The ruling enraged the white populations of the slave-holding states.