Ex Parte Kearney was a case heard by the United States Supreme Court in 1822. The case involved a dispute between two individuals, William Kearney and John Smith, over ownership of land located in what is now Alabama. At issue was whether or not Smith had obtained title to the land through an illegal transaction with Native Americans living on the property. The court held that Smith did not have valid title to the land because he had acquired it through fraud and deceitful means. Furthermore, they found that any agreement made between him and Native Americans would be void under federal law since such agreements were prohibited at this time period due to their potential for exploitation of indigenous peoples. As a result, Kearney retained his rightful claim as owner of the disputed property.

In Ex Parte Kearney, the Supreme Court was asked to decide whether a state court had jurisdiction over a case involving an alleged violation of federal law. The majority opinion held that the state court did not have jurisdiction because it lacked authority to enforce federal laws. However, Justice Johnson wrote a dissenting opinion arguing that states should be allowed to exercise their own powers in cases where there is no clear conflict with federal law. He argued that if Congress wanted exclusive control over such matters they would have explicitly stated so in the Constitution or other legislation. Furthermore, he noted that allowing states some degree of autonomy on this issue would help ensure uniformity and consistency across jurisdictions while still protecting individual rights under both state and federal laws.