During the American Civil War, Abraham Lincoln believed that dissenters remaining within loyal states posed a threat to the Union.
Throughout the war, his administration took several steps that expanded both federal and executive powers, such as declaring martial law, sanctioning arbitrary arrest and detention, and suspending the writ of habeas corpus. Lincoln justified these actions as necessary parts of war, but not everyone agreed.
On October 21, 1864, a military commission convened in Indianapolis to try Lambdin Milligan and his three accomplices for conspiracy against the US government, offering aid and comfort to the Confederates, and inciting rebellion. On December 10th, the commission found Milligan guilty and sentenced him to hang. Six months later, Milligan’s legal counsel filed a petition in the Circuit Court for a writ of habeas corpus, calling for a justification for Milligan’s arrest. The US Supreme Court finally decided this case on April 3, 1866.
In the Court’s decision, Ex parte Milligan, Chief Justice Salmon P. Chase declared that the military commission did not have jurisdiction to try and sentence Milligan because the Indiana courts remained in session and functioning during the war. Justice David Davis elaborated, stating that even during a period of suspension of habeas corpus—as was the case in 1864—citizens could only be detained, not tried or executed without charge. The Court decided that Milligan’s rights to personal liberty and the division between civilian and military justice had been jeopardized.
The American Civil War marks the beginning of many governmental, political, economic, social, and cultural changes. But in 1866, the US Supreme Court entered into the legal debate concerning the limitations of executive and federal power by standing on the side of personal liberty.