International humanitarian law requires states to ensure that the use of "a new weapon, means or method of warfare" is authorised. To comply with this obligation, when new weapons are studied with a view to equipping their armed forces, they must undergo a legality review. Companies designing equipment for the armed forces must include this review at the research and development stage.

Companies that design military equipment and dual-use goods and technologies shoulder significant responsibilities. To prevent the risk of corruption, that of using goods and technologies to commit serious violations, or of harming national interests, vigilance is required on many fronts. While major groups have dedicated teams and are often in the vanguard when it comes to compliance, the defence industry also consists of many SMEs and start-ups, for whom the subject may seem daunting. The aim of this guide is to help them with their initial thoughts on the subject.

As the movement to hold corporations to account for their participation in human rights violations grows, one sector in particular is at risk: the defence industry. Under the impulse of human rights organisations, several investigations and prosecutions are already ongoing to identify the role played by corporations and their executives in the war crimes and crimes against humanity allegedly perpetrated with equipment they sold to state and non-state actors. A number of factors explain the lack of readiness amongst legal departments facing such challenges. The main one seems, however, to reside in the overconfidence provided by the export licences delivered by their state. Corporations assume, mistakenly, that the licence to export awarded by the state shields them and their executives from criminal accountability.

A legal risk is arising for the defence industry: that of prosecutions against the company and its executives on the charges of complicity for international crimes. While the accountability of corporations for their role in war crimes and crimes against humanity was already addressed during the Second World War, with, for instance, the prosecution of Krupp during the Nuremberg Trial, it had somewhat been relinquished, becoming a substantial matter again only over the past twenty years. Increasingly, indeed, scholars have reflected on the responsibility arms manufacturers bear in the perpetration of war crimes, crimes against humanity and genocide, when these violations are perpetrated with the weapons they have sold to the alleged perpetrators. So have practitioners.