Lieber Code The Lieber Code of April 24 , 1863 , also known as Instructions for the Government of Armies of the United States in the Field , General Order № 100 , or Lieber Instructions , was an instruction signed by President Abraham Lincoln to the Union Forces of the United States during the American Civil War that dictated how soldiers should conduct themselves in wartime . It was named after the German - American jurist and political philosopher Francis Lieber . An abridged version of the Lieber Code was published in 1899 in " The War of the Rebellion : A Compilation of the Official Records of the Union and Confederate Armies " in 1899 . The main sections were concerned with martial law , military jurisdiction , and the treatment of spies , deserter s and prisoners of war . Ethical treatment . The document insisted upon the humane , ethical treatment of populations in occupied areas . It was the first expressly codified law that expressly forbade giving " no quarter " to the enemy ( i . e . , killing prisoners of war ) , except in such cases when the survival of the unit that held these prisoners was threatened . It forbade the use of poisons , stating that use of such puts any force who uses them entirely outside the pale of the ; it forbade the use of torture to extract confessions ; it described the rights and duties of prisoners of war and of capturing forces . It described the state of war , the state of occupied territories , the ends of war , and discusses permissible and impermissible means to attain those ends ; it discussed the nature of states and sovereignties , and insurrection s , rebellion s , and wars . As such , it is widely considered to be the first written recital of the customary law of war , in force between the civilized nations and peoples since time immemorial , and the precursor to the Hague Regulations of 1907 , the treaty - based restatement of the customary law of war . Slavery and Black Prisoners of War . The Lieber Code was probably commissioned by the Lincoln Administration to deal with the crisis touched off by Emancipation , which the Confederate States of America insisted was in violation of the customary rules of warfare . Moreover , Confederate officials such as Jefferson Davis had announced that the South would treat black Union soldiers as criminals , not as soldiers , subject to execution and re - enslavement upon capture . The Lieber Code defended the lawfulness of Emancipation under the laws of war and insisted that those same laws prohibited discrimination on the basis of color among combatants . One recent author says that the Code ' s association with Emancipation and the problem of black Union soldiers was so close that it ought to be called not Lieber ' s Code , but Lincoln ' s Code , since it was part and parcel of the most important decision of Lincoln ' s presidency . Sterner measures . Both the Lieber Code and the Hague Regulations of 1907 , which took much of the Lieber Code and wrote it into the international treaty law , included practices that would be considered illegal or extremely questionable by today ' s standards . In the event of the violation of the laws of war by an enemy , the Code permitted reprisal ( by musketry ) against the enemy ' s recently captured POWs ; it permitted the summary execution ( by musketry ) of spies , saboteurs , francs - tireurs , and guerrilla forces , if caught in the act of carrying out their missions . ( These allowable practices were later abolished by the Third and Fourth Geneva Convention s of 1949 , following the Second World War , which saw these practices in the hands of totalitarian states used as the rule rather than the exception to such . ) Such terms reflected Lieber ' s deep interest in the ideas of Prussian military strategist Carl von Clausewitz . They also arose out of one of the Code ' s central aims , which was not merely to limit the war , but to legitimate its expansion in the move to Emancipation and a more aggressive war effort . However , the code envisioned a reciprocal relationship between the population and the Army . As long as the population did not resist military authority , it was to be treated well . Should the inhabitants violate this compact by taking up arms and supporting guerrilla movements , then they were open to sterner measures . Among these were the imposition of fines , the confiscation and / or destruction of property , the imprisonment and / or expulsion of civilians who aided guerrillas , the relocation of populations , the taking of hostages , and the possible execution of guerrillas who failed to abide by the laws of war . It authorized the shooting on sight of all persons not in uniform acting as soldiers and those committing , or seeking to commit , sabotage . In the Civil War . Historians have often dismissed the role of the Code in the war effort . And while it is true that commanders such as William Tecumseh Sherman rarely if ever consulted the Code in making combat decisions , the Code played a significant role nonetheless in the war ' s last two years . It provided a blueprint for hundreds of military commissions charging law of war violations . And its provisions on black soldiers bolstered the Union ' s unpopular decision to cease prisoner exchanges so long as the South refused to exchange black prisoners on equal terms with white ones . In Europe . European jurists and treaty negotiators picked up Lieber ' s text and used it as the basis for negotiations that ultimately formed the basis of the Hague Convention of 1899 , the first multilateral treaty setting out terms for the laws of land warfare . Some features of the Code are still evident in the Geneva Conventions of 1949 . Philippine - American War . The Lieber Code was used extensively during the Philippine - American War as a justification and later a defense for actions against the native population ( see J . Franklin Bell and Littleton Waller ) . Numerous academics have questioned whether the acts of American forces , specifically the practice of reprisal by summary shooting of newly captured Filipino POWs , during the Philippine - American War , were , by the standards of the day , war crimes . Instead , these scholars suggest that many of the acts were the lawful exercise of the customary right of reprisal for war crimes and atrocities committed by Filipino insurrectionist forces against American POWs , and were conducted to demonstrate to the insurrectionist forces that failure to respect the rights of American POWs would result in reprisals against Filipino POWs . Credible allegations prompting American reprisals against Filipino forces included the roasting alive of American POWs over fires , as well as the burial of living American POWs to their neck in dirt , followed by use of insects ( specifically fire - ants ) as means of execution . Excesses by American forces in the carrying out of reprisals , such as extending them to non - combatants , were punished by court - martial . In addition , one unquestionable set of war crimes ( under the Lieber Code and the later Hague Regulations of 1907 ) did take place during the Philippine - American War : the torture of certain Filipino insurrectionists , uncovered by the Lodge Committee . One particularly common means of torture was the use of what was then known as the water cure , by American forces , in one instance “ . . . in order to secure information of the murder of Private O ' Herne of Company I , who had been not only killed , but roasted and otherwise tortured before death ensued . ”