The Lieber Code

The physical presence of the army declares the Martial Law and the ONLY the Martial Law ends is by Special Mention in the Treaty of Peace and by specific proclamation by the Commander in Chief and neither of those has happened.
“…Martial Law is the immediate and direct effect and consequence of occupation or conquest. The presence of a hostile army proclaims its Martial Law.” Article 1, Lieber Code [emphasis added]

“Martial Law does not cease during the hostile occupation, except by special proclamation, ordered by the commander in chief; or by special mention in the treaty of peace concluding the war,….” Article 2, Lieber Code [emphasis added]

Another way they can impose Martial Law is through bankruptcy.

Martial Law ONLY affects subjects and aliens
"Martial Law extends to property, and to persons, whether they are subjects of the enemy or aliens to that government." Article 7, Lieber Code

All Statutes are in support of the Martial Law
“Military jurisdiction is of two kinds: First, that which is conferred and defined by statute; second, that which is derived from the common law of war. Military offenses under the statute law must be tried in the manner therein directed; ….” Article 13, Lieber Code

All police are military police
"Martial Law affects chiefly the police and the collection of public revenue and taxes,..." Article 10 Lieber Code