15 Pet. (40 U.S.) 449 (1841), argued 12, 13, 15–18 Feb. 1841 and decided 10 Mar. 1841 by vote of 5 to 2; Thompson delivered the judgment of the Court but wrote only for himself and Wayne; Taney, McLean, and Baldwin concurring only in the result; McKinley and Story in dissent; Catron was absent for illness and Barbour had just died. Groves v. Slaughter involved explosive problems arising out of the relationship among slavery, the interstate slave trade, federal commerce power, and state police power. Mississippi by 1832 constitutional amendments prohibited the introduction of slaves into the state for sale, but did not enact legislation enforcing the prohibition. A purchaser defaulted on notes given for imported slaves, and the seller contended that the state constitutional prohibition was void because of conflict with the federal commerce power.
Justice Smith Thompson's opinion avoided the constitutional issues by holding that the constitutional prohibition was not self-executing. But Justice John McLean insisted on delivering a concurring opinion filled with crypto-abolitionist dicta, which provoked Chief Justice Roger B. Taney and Justice Henry Baldwin to deliver counterconcurrences refuting McLean's points with proslavery dicta. Taney and Baldwin both insisted that state control over slavery and African-Americans was exclusive of all federal power. The inability of the Court to cohere on, or even to evade, constitutional questions implicated by interstate commerce and slavery was symptomatic of deep divisions among the justices, which in turn reflected the emerging sectional controversy over slavery in the country.
William M. Wiecek