The body of international law applicable in times of armed conflict that:

• protects persons not or no longer taking a direct part in hostilities; and
• regulates permissible means and methods of warfare.

Everyone in situations of armed conflict: states, organised armed groups, multinational forces, civilians and the staff of private military/security companies ("PMCs/PSCs").

Unless they are part of the armed forces of a state, the staff of PMCs/PSCs are civilians. Accordingly:

• they may not be targeted;
• they may not take a direct part in hostilities.

If, however, the staff of PMCs/PSCs carry out acts that amount to taking a direct part in hostilities:

• they lose protection from attack during such participation;
• if captured they are not entitled to prisoner of war status and can be tried for mere participation in hostilities even if they have not committed any violations of international humanitarian law.

If they are operating in situations of armed conflict the staff of PMCs/PSCs must respect international humanitarian law and face criminal responsibility for any violations they may commit. This holds true whether they are hired by states, international organisations or by private companies.

Different measures both before and during a deployment are essential to ensuring that the staff of PMCs/PSCs respect international humanitarian law. These can include:

• vetting procedures for the hiring of staff;
• proper training in international humanitarian law;
• standard operating procedures and rules of engagement that comply with international humanitarian law;
• internal disciplinary procedures.

States cannot absolve themselves of their obligations under international humanitarian law by contracting PMCs/PSCs. They remain responsible for ensuring the relevant standards are met.

Should the staff of the PMCs/PSCs commit violations of international humanitarian law, the state that has hired them may be responsible if the violations can be attributed to it, in addition to the company and its staff.

States must ensure that the staff of such companies respects international humanitarian law. Important measures for achieving this include:

• requiring the staff to be properly trained in international humanitarian law;
• requiring that the PMCs/PSCs' rules of engagement and standard operating procedures comply with international humanitarian law.

Moreover, states must ensure that mechanisms exist for holding accountable the staff of PMCs/PSCs suspected of violating international humanitarian law and, possibly, the PMCs/PSCs themselves in civil proceedings.

All states have a responsibility to respect and ensure respect for international humanitarian law, including by the staff of PMCs/PSCs. States in whose territory PMCs/PSCs are incorporated or operate are in a particularly favourable position to affect their behaviour.
One way for the state of incorporation or operation to exercise some control and oversight could be by establishing a licensing/regulatory system. Key elements of a possible national regulatory framework could include:

• a prohibition of certain activities (e.g. direct participation in hostilities unless incorporated in the armed forces);
• a requirement that PMCs/PSCs obtain operating licences based on meeting certain criteria, including requirements that the PMCs/PSCs:
• train their staff in IHL;
• adopt standard operating procedures/rules of engagement that respect IHL;
• adopt appropriate disciplinary measures;
• a requirement for authorisation for every contract depending on the nature of the proposed activities and the situation in country where will operate; and
• sanctions for operating without having obtained the necessary authorisations or in violation thereof (e.g. withdrawal of operating licence, loss of bond, criminal sanctions…).

Such a regulatory system should be complemented by a functioning system for bringing to justice those accused of having committed violations of international humanitarian law.