General Ambrose E. Burnside had former-Congressman Clement Vallandigham arrested in May 1863 for continuing to express sympathy for the Confederate cause after having been warned to cease doing so. Vallandigham was tried by a military tribunal and sentenced to two years in a military prison. Lincoln quickly commuted his sentence to banishment to the Confederacy. Vallandigham appealed his sentence, arguing that the Enrollment Act did not authorize his trial by a military tribunal rather than in ordinary civilian courts, that he was not ordinarily subject to court martial, and that Gen. Burnside could not expand the jurisdiction of military courts on his own authority. The Supreme Court did not address the substance of Vallandigham's appeal, instead denying that it possessed the jurisdiction to review the proceedings of military tribunals without explicit congressional authorization.