International arms sales are a thriving business giving rise to a host of legal concerns for both the supplying and the recipient countries. How much due diligence is a ‘sending’ state required to engage in before weapons are sold? Does state authorization effectively obviate the existence of fault in corporate officials supplying arms later to be used in the commission of war crimes? Finally, to what extent will the new Arms Trade Treaty change state practice? This contribution briefly examines some of the above-mentioned concerns with reference to the recent submission by the European Centre for Constitutional and Human Rights (ECCHR) to the International Criminal Court in which the ECCHR advocates for the opening of preliminary examinations into the conduct of several European companies supplying arms to the Saudi/UAE-led coalition in the context of the war in Yemen.