In Swaim v. United States (1896), the U.S. Supreme Court ruled on a case involving military law and court-martial proceedings. The appellant, Winfield Scott Swaim, was an army officer who had been convicted by a general court-martial of conduct unbecoming an officer and gentleman, as well as other charges related to financial improprieties while serving in the Quartermaster's Department. He appealed his conviction arguing that he was denied due process because some members of the court martial panel were biased against him. The Supreme Court rejected this argument stating that courts-martial are not required to adhere strictly to common-law rules regarding jury impartiality since they operate under different principles derived from necessity and public duty. It held that allegations of bias must be substantial enough to discredit the fairness or integrity of such proceedings. Furthermore, it stated that even if there were errors in procedure during trial or sentencing phase at lower level courts martial these did not necessarily invalidate convictions unless they resulted in substantial prejudice against accused which wasn't proven here by Swaim. Thus upholding his conviction, this decision reinforced broad discretion given to military tribunals within their jurisdictional boundaries thereby establishing important precedent for future cases involving military justice system.

In the dissenting opinion for Swaim v. United States, Justice Harlan argued that the military court did not have jurisdiction to try Lieutenant Swaim because he was not in active service at the time of his trial. He contended that under Article 61 of the Articles of War, a person must be in actual service or on full pay when an offense is committed to be subject to military law. In this case, Lt. Swaim was on leave without pay and therefore should have been tried by a civil court instead. Furthermore, Justice Harlan disagreed with how evidence from previous trials had been used against Lt. Swaim during his court-martial proceedings; such use violated principles of double jeopardy and due process rights according to him.