In the case of Jennet Smith, Calvin S. Powe and Thomas A. Powe v Joseph Kernochan, the Supreme Court was asked to decide whether a contract between two parties could be enforced if it had been made in violation of an existing state law. The plaintiffs argued that they had entered into a valid contract with Kernochan for the sale of certain slaves and were entitled to damages when he failed to fulfill his obligations under it. However, Kernochan argued that since their agreement violated Maryland's laws prohibiting such contracts, it was not enforceable in court. After considering both sides' arguments, the Supreme Court ultimately ruled in favor of Kernochan on grounds that any contract which violates public policy is void and unenforceable by either party regardless of its terms or conditions. This decision established an important precedent regarding how courts should interpret contracts which violate existing statutes or regulations going forward

In the case of Jennet Smith, Calvin S. Powe, and Thomas A. Powe v Joseph Kernochan, Justice McLean delivered a dissenting opinion in which he argued that the lower court's decision should be reversed because it was based on an erroneous interpretation of Georgia law. He believed that under Georgia law, slaves were considered personal property and could not be held liable for debts incurred by their owners without express authorization from the owner or legal representative. Furthermore, Justice McLean argued that even if such authorization had been given in this case, it would have been invalid since there was no evidence to support its validity as required by Georgia law at the time. Therefore, he concluded that Kernochan did not have a valid claim against Smith et al., and thus his suit should have been dismissed instead of being granted judgment against them as it had been in the lower court ruling.