In the 1949 case of Hiatt, Warden v. Brown, the United States Supreme Court ruled on a habeas corpus petition from a prisoner who claimed that his court-martial was unconstitutional because it included an officer who had previously acted as investigator in his case. The petitioner argued this violated the Fifth Amendment's guarantee against double jeopardy and due process rights. However, the Supreme Court disagreed with him and upheld his conviction by military tribunal for murder committed while he was serving overseas during World War II. The court held that there is no constitutional requirement for separation between investigatory and adjudicative functions in military tribunals; therefore, having an investigating officer also serve on a court-martial panel does not violate any constitutional rights or protections under U.S law. Furthermore, they stated that courts should give considerable deference to decisions made by military tribunals given their unique role within our system of government.

In the dissenting opinion for Hiatt v. Brown, Justice Robert H. Jackson disagreed with the majority's decision to uphold a military court-martial conviction of a civilian in peacetime. He argued that this ruling violated constitutional rights and principles by extending military jurisdiction beyond its intended scope, which is limited to active duty personnel during times of war or declared emergency. He contended that such an extension could potentially lead to abuse of power and undermine civil liberties if left unchecked. Furthermore, he expressed concern over the lack of due process protections in military tribunals compared to civilian courts, including restrictions on legal representation and appeal rights. In his view, these factors combined made it inappropriate for civilians like Brown - who was no longer serving in the army at the time charges were brought against him - to be subjected to court-martial proceedings.