If you serve in the military in a combat-oriented role, it's critical that you know the laws and regulations that dictate how you can fight. If you fail to abide by the rules of engagement, you could face serious consequences, and potentially prison time.

In this guide, we'll give you a general overview of the rules of engagement most likely to affect you as a member of the U.S. military. We'll also cover restricted weapons and equipment, things you'll need to know if you conduct joint operations with another country's military and the general principles governing how and when you can use lethal force.

Laws of War

Every military conflict is subject to national and international laws of war. Several governing bodies create these laws, and they often interact in legally complex ways.

• The U.S. Law of War is a formal code of conduct that all U.S. troops are expected to know and obey.

• The Geneva Convention applies to all soldiers, regardless of what country they're from or where they're operating.

• The Hague Conventions govern warfare tactics and the use of weapons.

• North Atlantic Treaty Organization (NATO) guidelines further specify what NATO member countries can and cannot do in war.

Each of these sets of laws contain many different (and sometimes contradictory) rules and regulations. Each nation's government interprets these standards and issues its own rules of engagement to its soldiers. In the event that two or more laws applicable to you contradict one another, you must abide by the most restrictive one. Note that the terms "laws of war" and "rules of engagement" are not interchangeable. Rules of engagement are more specific than the laws of war, so it's possible (although very rare) for an action to abide by the laws of war but violate rules of engagement.

Rules of Engagement

There are several different kinds of rules of engagement "templates" that apply to different kinds of armed conflicts. As a member of the U.S. military, you're most likely to encounter one of three scenarios:

• Peace-keeping operations require the consent of all nations involved and are essentially "night watchman" operations. Military personnel in these areas function more like policemen; their primary role is to defend people and property from hostile (and usually non-military) forces in the area.

• U.S. military personnel in active combat with declared hostile forces are subject to a different set of rules that are less restrictive than those associated with peace-keeping operations.

• Special Forces units and other elite fighters are governed by still other sets of rules. In many respects, top-tier operatives have the most freedom to engage hostile forces, but their missions often require congressional approval or other special, high-level authorization.

Rules of engagement dictate:

• Who you can shoot at and under which circumstances
• The buildings and infrastructure you can target
• The weapons and equipment you're allowed to use
• Your legal obligations to aid or protect noncombatants
• The treatment and transfer of prisoners (read about what to do if you're captured by enemy forces)

To further complicate matters, rules of engagement often vary between different forces involved in the same conflict. If, for instance, you find yourself fighting alongside French, British or Australian allies, each military will almost invariably have a different set of rules to obey.

When possible, your commanders will coordinate with one another to issue operation-specific rules of engagement. The goal in such cases is to enable military personnel from different countries to work together under a consistent set of rules that still fall within the international laws of war. However, such proactive coordination isn't always possible or timely. If you're unsure of which rules apply to you in joint operations, default to your standard RoE card or consult your superiors for guidance.

RoE Pocket Cards

Military commanders know that the rules of engagement are myriad and complex. They don't expect their subordinates to individually keep up with the ever-changing, politically charged laws of war. To make things a little more manageable, commanders are responsible for issuing and updating RoE pocket cards — succinct, single-page summaries of the rules you're expected to obey in the course of a given operation.

RoE cards, although convenient, are not a replacement for official training on the rules of engagement, which you'll receive prior to deploying to a combat zone. Because they're so concise, they're inevitably incomplete and will contain only the most basic information that is relevant to your particular unit. They contain mission-specific information and are often written in anticipation of future changes. For this reason, they typically use language like "As of [date]." This way, you can easily compare different versions of RoE cards to identify the most current rules.

Example U.S. Military Rules of Engagement

In this section, we'll review an actual RoE card issued to U.S. military personnel in Iraq and Afghanistan in 2003. This card is outdated now, but that's partly the point — any attempt to cover current RoE would soon become outdated (and its content may not apply to your particular unit or operation anyway). Still, this card has typical rules of engagement that you're likely to see in most wartime scenarios.

1. On order, enemy military and paramilitary forces are declared hostile and may be attacked subject to the following instructions:
   1. Positive identification (PID) is required prior to engagement. PID is a reasonable certainty that the proposed target is a legitimate military target. If no PID, contact your next higher commander for decision.
   2. Do not engage anyone who has surrendered or is out of battle due to sickness or wounds.
   3. Do not target or strike any of the following except in self-defense to protect yourself, your unit, friendly forces, and designated persons or property under your control:
      • Civilians
      • Hospitals, mosques, national monuments, and any other historical and cultural sites
   4. Do not fire into civilian populated areas or buildings unless the enemy is using them for military purposes or if necessary for your self-defense. Minimize collateral damage.
   5. Do not target enemy infrastructure (public works, commercial communication facilities, dams), Lines of Communication (roads, highways, tunnels, bridges, railways) and Economic Objects (commercial storage facilities, pipelines) unless necessary for self-defense or if ordered by your commander. If you must fire on these objects to engage a hostile force, disable and disrupt but avoid destruction of these objects, if possible.
2. The use of force, including deadly force, is authorized to protect the following:
   1. Yourself, your unit, and friendly forces
   2. Enemy Prisoners of War
   3. Civilians from crimes that are likely to cause death or serious bodily harm, such as murder or rape
   4. Designated civilians and/or property, such as personnel of the Red Cross/Crescent, UN, and US/UN supported organizations
3. Treat all civilians and their property with respect and dignity. Do not seize civilian property, including vehicles, unless you have the permission of a company level commander and you give a receipt to the property's owner.
4. Detain civilians if they interfere with mission accomplishment or if required for self-defense.
5. CENTCOM General Order No. 1A remains in effect. Looting and the taking of war trophies are prohibited.

REMEMBER:

• Attack enemy forces and military targets.
• Spare civilians and civilian property, if possible.
• Conduct yourself with dignity and honor.
• Comply with the Law of War. If you see a violation, report it.
• These ROE will remain in effect until your commander orders you to transition to post-hostilities ROE.

Principles Governing Use of Force

When military commanders interpret the laws of war and issue rules of engagement to their troops, they do so with respect to the general principles of the use of military force. Irrespective of any narrower restrictions you may encounter, you're also expected to weigh these three considerations before you fire your weapon at people or property.

• Establish the necessity of using force in response to a credible threat.
• Attempt to de-escalate and eventually resolve the situation without force, if possible.
• Respond with proportional force — that is, force sufficient to end the threat and no more.

In the heat of combat, or during a standoff, you may not have time to think carefully about the details of the situation. That's why it's so important to contemplate likely scenarios ahead of time (for instance, the application of the rules of engagement in combating guerilla warfare tactics) and to practice making quick decisions during combat training.

Permitted and Restricted Equipment

The Hague Conventions and other bodies of law broadly prohibit the use of any weapon that inflicts "undue suffering" or that carries an unacceptable risk of unintentional or unnecessary damage to civilians or infrastructure. You may be wondering who defines terms like "undue suffering" and "unnecessary damage" in any given conflict. It's a good question without a simple answer. Certain types of weapons are universally banned, whereas others, such as missiles, bombs, grenades and mines are permitted in certain situations (read our military service member's guide to mines and military service member's guide to grenades for more information on these weapons).

The Hague Convention of 1907 (more specifically its Geneva Protocol, adopted in 1925) permanently bans the use of all chemical and biological weapons in warfare. The Biological and Chemical Weapons Conventions of 1972 and 1993, respectively, further define and more precisely restrict these weapons.

Contrary to popular belief, flamethrowers are not banned in war, they just haven't been used by the U.S Military for several decades. This is largely because, since the 90s, our military has been in combat primarily in areas where there's nothing to burn — places like Iraq and Afghanistan. Contrast these theaters against those in Vietnam and Korea, which have much more foliage.

The list of restrictions on certain types of weapons and equipment is a pretty long one, but as a modern-day soldier, you'll probably never encounter most of them. The vast majority of U.S. military personnel use small arms and artillery that fall squarely within the confines of the laws of war. Although you're permitted to use enemy weapons and equipment in an emergency, you must still abide by the rules of engagement. If you're ever in doubt about the legality of weapons or equipment, consult your commander for guidance.

When you're deployed in a combat zone, getting home alive is often the only thing on your mind, and understandably so. War is taxing, even when it's morally justified, and easy decisions are rare in combat. Even so, it's important to become thoroughly familiar with the rules of engagement so that you can act honorably during combat.