If you are a member of the military, you need to be especially careful about keeping yourself out of legal trouble. You could find yourself facing charges in two courts.
The Yale Law Journal explains that if you face charges in a criminal court, you could also have to face them in military court.
You may wonder how you can face the same charges twice when federal law provides every person protection against double jeopardy or facing charges for one crime more than once. The idea of double jeopardy does not come into play between military and civilian courts.
The military can court-martial you on a crime even if you have already gone through the court system because of the same reason why you could face charges for the same crime in state and federal courts. It is the doctrine of separate, or dual, sovereigns.
This law says that double jeopardy only applies to each sovereign. This means that the state cannot try you twice for the same crime or the military cannot try you twice for the same crime. It does apply to different court systems.
This concept can be confusing because most people understand double jeopardy in basic terms. They do not understand how each court system is a separate entity. Compounding the confusion is that the state and federal courts usually do not compete, meaning if you face charges in state court for a crime, the federal court will not usually go after you for the same crime. The same is not true for the military. You could find yourself in a court-marital even if you have already gone through a trial for the matter in state or federal court.