In United States v. Halleck et al., the Supreme Court ruled on a case involving two men, William W. Halleck and John C. Kelton, who had been convicted of violating the Neutrality Act of 1794 by conspiring to aid Confederate forces during the Civil War. The defendants argued that they were not guilty because Congress did not have authority under Article I Section 8 Clause 10 of the Constitution to pass such an act as it was outside their enumerated powers; however, this argument was rejected by Chief Justice Salmon P Chase in his majority opinion for the court which held that Congress had acted within its constitutional power when passing this law and thus could enforce it against individuals like Halleck and Kelton who violated it. Furthermore, he noted that while some may disagree with or oppose laws passed by Congress due to political differences or personal beliefs, citizens must still abide by them regardless if they are found unconstitutional at a later date since courts cannot retroactively invalidate laws already enforced upon conviction unless expressly stated otherwise in said law itself.

In United States v. Halleck et al., the Supreme Court was asked to decide whether a military court had jurisdiction over civilians accused of aiding and abetting Confederate forces during the Civil War. The majority opinion held that it did, but Justice Field dissented. He argued that Congress had not given any authority for such trials in its legislation or regulations, and thus they were unconstitutional under Article III of the Constitution which grants judicial power only to courts established by law. Furthermore, he argued that even if Congress had granted such authority, it would be an infringement on civil liberties as no civilian should be subject to military justice without due process protections like those available in civil courts. Finally, he noted that allowing these kinds of proceedings could lead to further abuses against citizens' rights since there is less oversight from other branches of government when dealing with matters related to national security than with ordinary criminal cases heard in civilian courts.