The development and use of new military technologies raises many ethical issues. Simply examining the law regarding the use of such technologies does not capture many of these issues, since while there is certainly an intimate relationship between law and ethics, the questions raised by these two disciplines differ. Perhaps the soldier of the future might simply enter into battle in a virtual sense, by piloting a remotely controlled device, or managing attacks against the enemy’s computer systems through cyber warfare. But whatever the future may be, it is impossible to get a sense of what the laws governing armed violence ‘ought’ to be without considering the ethical issues that such new military technologies raise. This chapter considers the issues which new military technologies raise both with regard to jus ad bellum (justice of war) and jus in bello (justice in war).