Wilson, ex parte was a case heard by the United States Supreme Court in 1809. The case involved William Wilson who had been convicted of murder and sentenced to death. He appealed his conviction on the grounds that he had not received due process under Virginia law at the time of his trial. Specifically, he argued that he should have been allowed to challenge jurors for cause before they were selected as jurors in his trial. The court agreed with Wilson's argument and reversed his conviction based on this violation of due process rights. This decision established an important precedent which has since become known as "the right to challenge prospective jurors." It is now recognized as one of the most fundamental constitutional protections afforded criminal defendants during jury selection proceedings in all U.S courts today

In Wilson, ex parte, the Supreme Court was asked to decide whether a state court had the authority to issue a writ of habeas corpus for an individual who had been convicted in federal court. The majority opinion held that it did not have such power. Justice Johnson wrote a dissenting opinion arguing that states should be allowed to issue writs of habeas corpus when necessary and proper under their own laws. He argued that this would help ensure justice by allowing individuals access to relief from unlawful imprisonment or detention without having to rely solely on federal courts. Furthermore, he believed that denying states this power could lead them into conflict with Congress over matters concerning citizens' rights and liberties which were traditionally within their purview as sovereign entities. Ultimately, Johnson concluded that if Congress wanted exclusive control over these matters then they should pass legislation explicitly stating so rather than relying on judicial interpretation alone.