This brochure explains why, when and how international humanitarian law (IHL) is relevant to private businesses. It is primarily intended for businesspeople, particularly corporate legal counsel and others in corporate compliance or human rights due diligence roles. However, it also aims to answer questions that humanitarian practitioners, legal experts, government officials and others frequently ask about business and IHL. Accordingly, additional technical information on several issues is provided in breakout boxes. Businesses need to be aware of and prepared to seek advice about IHL whenever there is a possibility their oper ations, supply chains, partnerships or investments may affect or be affected by a situation of armed conflict. A business may expand its operations or relationships in ways that bring it into contact with an armed con f lict, or an armed conflict may break out in a place where a business is already involved. Either way, such situations can present new and unfamiliar risks. What a business does or does not do in such circumstances can have important consequences for affected civilian populations, as well as its own personnel and assets. Beyond the harm to victims, being involved in IHL violations can negatively impact a business’ reputation, operations and financial situation. Businesses are increasingly aware of their human rights responsibilities. Many have adopted policies that align with initiatives like the United Nations Global Compact and the United Nations Guiding Principles on Business and Human Rights (see the breakout box below). In situations of armed conflict, international human rights law remains relevant, but IHL takes on an essential role as it is a separate set of specialized rules that aim to limit suffering during situations of armed conflict. IHL directly binds all individuals whose activities are sufficiently connected to an armed conflict. This can include the personnel of private business entities, depending on what they do. This means that under inter national law, IHL can directly apply to the operations of a private business. Business activities that physically take place in a country where an armed conflict is occurring may be more likely to become subject to IHL. However, other kinds of relationships can also make IHL relevant to a private business, even when its personnel and assets are not physically located where the conflict is taking place. If violations of IHL occur, private businesses and their personnel can be subject to civil liability or criminal liabil ity under international or national laws. States have obligations under IHL to ensure that private individuals and businesses under their authority respect IHL, including through enacting and enforcing national legislation. Humanitarian, reputational and operational considerations should also prompt a business to recognize its responsibility to ensure respect for IHL by its personnel and to promote respect for IHL by others with whom it has relationships. These could include government authorities or non state armed groups, other private business entities that are its customers or in its supply chain, as well as any entities in which it invests or to which it provides financial services. IHL also protects the personnel and assets of businesses. IHL restricts the circumstances in which parties to a conflict can seize, damage or destroy private property. Personnel and assets may not be directly attacked as long as they retain their civilian character. Even attacks targeting a valid military target are prohibited if the inciden tal damage to civilians and civilian objects, including the personnel and assets of businesses, would be expected to be disproportionate. However, the decisions a business takes on the activities of its personnel and the use of its assets can also result in its personnel and assets losing protection, thus being exposed to higher risks. For all these reasons, businesses need to be familiar with the rules of IHL that are relevant to their operations or that may become relevant to them. This brochure aims to improve this awareness and understanding, and to highlight further resources to help private business actors adopt appropriate policies and practices.