In general the civil laws of the invaded state continue in force in so far as they do not affect the hostile occupant unfavorably. The regular judicial tribunals continue to act in cases not affecting the military occupation. Administrative officers continue to perform their functions in absence of orders to the contrary, though of course purely political officers would be limited in the exercise of their functions; e.g. registrars of marriages, births, and deaths might act as usual, while the authority of a governor might be suspended. There is no doubt that the freedom of the press cannot be claimed, as this might bring grave consequences upon the occupying force.
The belligerent occupant may destroy or appropriate public property which may have a hostile purpose, as forts, arms, armories, etc. The occupying force may enjoy the income from the public sources. Strictly private property should be inviolable, except so far as the necessity of war requires contrary action.
Means of transportation, railways, boats, etc., as of direct use in military operations, can be appropriated for the use of the invader. "Their destruction is forbidden, unless it be required by the necessities of war. They are restored, at the peace, in the state in which they then are."[332]
The invader is bound to give such measure of protection to the inhabitants of the occupied territory as he is able.[333]
Belligerent occupation begins when an invaded territory is effectively held by a military force.
[§ 109. Forbidden Methods]
In the conduct of hostilities certain methods of action and certain instruments are generally forbidden.
Deceit involving perfidy is forbidden.[334] As there are certain conventional agreements held to exist even between enemies, violations of these agreements remove from the violator the protection of the laws of war. On land it is not permitted to use the flag or uniform of the enemy for purposes of deceit.[335] Article 7 of the Naval War Code of the United States provides that "The use of false colors in war is forbidden, and when summoning a vessel to lie to, or before firing a gun in action, the national colors should be displayed by vessels of the United States."[336] Not all authorities agree in regard to the provision forbidding false colors, though agreeing upon the other provisions. The use of the conventional flag of truce, a white flag, or of the hospital flag, red cross on white ground, to cover military operations or supplies is forbidden.[337] Stratagems, such as feigned attacks, ambush, and deceit not involving perfidy are allowed.[338] Assassination by treachery is forbidden.[339]
"The bombardment, by a naval force, of unfortified and undefended towns, villages, or buildings is forbidden, except when such bombardment is incidental to the destruction of military or naval establishments, public depots of munitions of war, or vessels of war in port, or unless reasonable requisitions for provisions and supplies essential at the time to such naval vessel or vessels are forcibly withheld, in which case due notice of bombardment shall be given. The bombardment of unfortified and undefended towns and places for the nonpayment of ransom is forbidden."[340]
By the declaration of the Hague Conference of 1898, "the contracting parties agree to prohibit, for a term of five years, the launching of projectiles and explosives from balloons or by other new methods of a similar nature."[341]