Hague Convention of 1899

I wanted to learn more about bullet types after watching an explanation on the types of ammo and guns that would need to be created to function in Japanese mech cartoon, Patalabor this time. Did you think dum dum bullets were weaker than an average bullet, well you we're wrong like me. They expand on impact, taking a bigger bite out of you. Check out Sir John Ardagh defending there use in the Hague Convention of 1899 where they were banned from war. Since then the laws been expanded on and using them in war is a war crime or technically ammo called expanding bullets are not allowed

"The civilized soldier when shot recognizes that he is wounded and knows that the sooner he is attended to the sooner he will recover. He lies down on his stretcher and is taken off the field to his ambulance, where he is dressed or bandaged. Your fanatical barbarian, similarly wounded, continues to rush on, spear or sword in hand; and before you have the time to represent to him that his conduct is in flagrant violation of the understanding relative to the proper course for the wounded man to follow—he may have cut off your head." However, the rest of the delegates at the Hague Convention 1899 did not accept this justification and voted 22–2 to prohibit the future use of the dumdum bullet.
 -Sir John Ardagh from Wikipedia