ns, where war really prevails,
there is a necessity to furnish a substitute for the civil authority,
thus overthrown, to preserve the safety of the army and society; and as
no power is left but the military, it is allowed to govern by martial
rule until the laws can have their free course. As necessity creates the
rule, so it limits its duration; for, if this government is continued
_after_ the courts are reinstated, it is a gross usurpation of power.
Martial rule can never exist where the courts are open, and in proper
and unobstructed exercise of their jurisdiction. It is also confined to
the locality of actual war."[82] Four Justices, speaking by Chief
Justice Chase, while holding Milligan's trial to have been void because
violative of the act of March 3, 1863 governing the custody and trial of
persons who had been deprived of the _habeas corpus_ privilege, declared
their belief that Congress could have authorized Milligan's trial. Said
the Chief Justice: "Congress has the power not only to raise and support
and govern armies but to declare war. It has, therefore, the power to
provide by law for carrying on war. This power necessarily extends to
all legislation essential to the prosecution of war with vigor and
success, except such as interferes with the command of the forces and
the conduct of campaigns. That power and duty belong to the President as
Commander in Chief. Both these powers are derived from the Constitution,
but neither is defined by that instrument. Their extent must be
determined by their nature, and by the principles of our institutions.
* * * We by no means assert that Congress can establish and apply the
laws of war where no war has been declared or exists. Where peace exists
the laws of peace must prevail. What we do maintain is, that when the
nation is involved in war, and some portions of the country are invaded,
and all are exposed to invasion, it is within the power of Congress to
determine in what States or districts such great and imminent public
danger exists as justifies the authorization of military tribunals for
the trial of crimes and offences against the discipline or security of
the army or against the public safety."[83] In short, only Congress can
authorize the substitution of military tribunals for civil tribunals for
the trial of offenses; and Congress can do so only in wartime.

MARTIAL LAW IN HAWAII

The question of the constitutional status of martial law was raised in
Worl