Lieber Code 1863: Section V
SECTION V.–Safe-conduct–Spies– War-traitors– Captured messengers– Abuse of the flag of truce.
86. All intercourse between the territories occupied by belligerent armies, whether by traffic, by letter, by travel, or in any other way, ceases. This is the general rule, to be observed without special proclamation.
Exceptions to this rule, whether by safe-conduct or permission to trade on a small or large scale, or by exchanging mails, or by travel from one territory into the other, can take place only according to agreement approved by the
Government or by the highest military authority.
Contraventions of this rule are highly punishable.
87. Ambassadors, and all other diplomatic agents of neutral powers accredited to the enemy may receive safe-conducts through the territories occupied by the belligerents, unless there are military reasons to the contrary, and unless they may reach the place of their destination conveniently by another route. It implies no international affront if the safe-conduct is declined. Such passes are usually given by the supreme authority of the state and not by subordinate officers.
88. A spy is a person who secretly, in disguise or under false pretense, seeks information with the intention of communicating it to the enemy.
The spy is punishable with death by hanging by the neck, whether or not he succeed in obtaining the information or in conveying it to the enemy.
89. If a citizen of the United States obtains information in a legitimate manner and betrays it to the enemy, be he a military or civil officer, or a private citizen, he shall suffer death.
90. A traitor under the law of war, or a war-traitor, is a person in a place or district under martial law who, unauthorized by the military commander, gives information of any kind to the enemy, or holds intercourse with him.
91. The war-traitor is always severely punished. If his offense consists in betraying to the enemy anything concerning the condition, safety, operations, or plans of the troops holding or occupying the place or district, his punishment is death.
92. If the citizen or subject of a country or place invaded or conquered gives information to his own government, from which he is separated by the hostile army, or to the army of his government, he is a war-traitor, and death is the penalty of his offense.
93. All armies in the field stand in need of guides, and impress them if they cannot obtain them otherwise.
94. No person having been forced by the enemy to serve as guide is punishable for having done so.
95. If a citizen of a hostile and invaded district voluntarily serves as a guide to the enemy, or offers to do so, he is deemed a war-traitor and shall suffer death.
96. A citizen serving voluntarily as a guide against his own country commits treason, and will be dealt with according to the law of his country.
97. Guides, when it is clearly proved that they have misled intentionally, may be put to death.
98. All unauthorized or secret communication with the enemy is considered treasonable by the law of war.
Foreign residents in an invaded or occupied territory or foreign visitors in the same can claim no immunity from this law. They may communicate with foreign parts or with the inhabitants of the hostile country, so far as the military authority permits, but no further. Instant expulsion from the occupied territory would be the very least punishment for the infraction of this rule.
99. A messenger carrying written dispatches or verbal messages from one portion of the army or from a besieged place to another portion of the same army or its government, if armed, and in the uniform of his army, and if captured while doing so in the territory occupied by the enemy, is treated by the captor as a prisoner of war. If not in uniform nor a soldier, the circumstances connected with his capture must determine the disposition that shall be made of him.
100. A messenger or agent who attempts to steal through the territory occupied by the enemy to further in any manner the interests of the enemy, if captured, is not entitled to the privileges of the prisoner of war, and may be dealt with according to the circumstances of the case.
101. While deception in war is admitted as a just and necessary means of hostility, and is consistent with honorable warfare, the common law of war allows even capital punishment for clandestine or treacherous attempts to injure an enemy, because they are so dangerous, and it is difficult to guard against them.