"they'll be doing something with some very special people"
NG works for Governor under Title 32 can perform Homeland defense functions and OOTW, operations other than war. When Federalized, under Title 10, they're used for war.
Marines can provide all support (tactics, intel training, equipment, vehicles, security overwatch) to NG when they are performing Homeland Defense and OOTW.
Lincoln held Military Tribunals to deal with insurrection and disloyalty, even in places where there was no war, including in non-rebelling states. He was found to have exceeded the limits of his authority. The Supreme Court Decision in this case, Ex Parte Milligan, describes the circumstances in which the President can use troops, (Title 32 NG supported by Active Duty) on US soil.
The entire case lies on whether the courts are considered open or not. If courts of justice CLOSED
Facts:
Lambdin P. Milligan was arrested by the command of General Alvin P. Hovey for certain charges that are not discussed. He was taken into custody and sentenced to be hanged. He petitioned to the Circuit Court of the United States for the District of Indiana to be discharged from his imprisonment.
Issue
Does the military have jurisdiction to try and convict Lambdin P. Milligan?
Holding
No, the military does not have jurisdiction over Lambdin P. Milligan because they courts were open and able to hear cases.
Reasoning
The Constitution says that everybody is entitled to a trial by jury. The Constitution specifically states, “in all criminal prosecutions the accused shall enjoy the righto a speedy and public trial by an impartial jury of the state and district wherein the crime shall have been committed…” Our founding fathers put those words into the Constitution because they wanted everybody to have fair treatment when fighting their case.
The military only has power to control the judicial branch when the courts are not open and the people are in immediate danger. Indiana was one of the states that were not being rebellious. Therefore, the military did not have authority to act as a court and have trials. This is one of Milligan’s rights that were violated. Milligan was also denied a trial by jury. He was tried and convicted by a military commission.
Martial law can only exist when judicial law does not. These two do not coexist. Martial law is defined as when the “commander of an armed force… has the power… to suspend all civil rights and their remedies, and subject citizens… to the rule of his will…” Martial law can only be used when the courts are closed and society is in an uproar. Martial law cannot be applied to this case unless the dangers were in the state of Indiana. There must be an invasion that is “present and actual” in order for martial law to apply. Just a threat is not enough to apply martial law. Thus, the military had no authority to try and convict Lambdin P. Milligan.
are not available to the people, then it is the Executive's duty to provide them using the tools provided which includes federal troops.
http://www.casebriefsummary.com/ex-parte-milligan/