Related Rule
Philippines
Practice Relating to Rule 158. Prosecution of War Crimes
The Joint Circular on Adherence to IHL and Human Rights (1991) of the Philippines provides:
All human rights-related incidents allegedly committed by members of the AFP [Armed Forces of the Philippines] and PNP [Philippine National Police] in the course of security/police operations shall be immediately investigated and if evidence warrants, charges shall be filed in the proper courts. Reports of investigation as well as actions taken shall be submitted to GHQ or PNP HQs fifteen (15) days after receipt of information about the alleged human rights violation. [The] same shall be forwarded to the Department of National Defense or Department of Interior and Local Government. 
Philippines, Implementation Guidelines for Presidential Memorandum Order No. 393, dated 9 September 1991, Directing the Armed Forces of the Philippines and the Philippines National Police to Reaffirm their Adherence to the Principles of Humanitarian Law and Human Rights in the Conduct of Security/Police Operations, Joint Circular Number 2-91, Department of National Defense, Department of Interior and Local Government, 1991, § 2(b)(1).
The War Crimes Trial Executive Order (1947) of the Philippines provides for a list of punishable offences including “violations of the laws and customs of war” and other specified acts committed “before or during the war … whether or not in violation of the local laws”. 
Philippines, War Crimes Trial Executive Order, 1947, § II(b)(2) and (3).
In the Cantos case before the Philippine Supreme Court in 1946, the Court dismissed (in a majority opinion) a petition for habeas corpus made by a Japanese/Philippine civilian, finding that the petitioner was subject to the jurisdiction of a US military commission. In its judgment, the Court noted:
It is well settled that war crimes may be committed not only by lawful belligerents but by any “men and bodies of men, who, without being lawful belligerents” “nevertheless commit hostile acts of any kind.” (Par. 351, Rules of Land Warfare.) “Persons of the enemy territory who steal within the lines of hostile army for the purpose of robbing, killing, etc.” are also war criminals subject to the jurisdiction of military commissions. (Par. 352, id., id.) And in the preamble to the Hague Convention it is declared that “until a more complete code of the laws of war has been issued, the High Contracting Parties deem it expedient to declare that, in cases not included in the Regulations adopted by them, the inhabitants and the belligerents remain under the protection and the rule of the principles of the law of nations, as they result from the usages established among civilized peoples, from the laws of humanity, and the dictates of the public conscience.”
Here, the petitioner is a Filipino citizen though of a Japanese father, and associating himself with Japan in the war against the United States of America and the Philippines, committed atrocities against unarmed and noncombatant Filipino civilians and looted Filipino property. He is, indeed, a war criminal subject to the jurisdiction of the military commission, and his confinement by the respondent is not illegal. (In re Yamashita, 66 Sup. Ct., 340; 90 Law. ed., 499.) 
Philippines, Supreme Court, Cantos case, Judgment, 28 June 1946.