War crimes have been a consistent feature of the Syrian conflict since its inception. Indeed, a map of the war crimes committed in Syria reads like a survey course of the topic. The Syrian people have witnessed and experienced siege warfare; deliberate, indiscriminate, and disproportionate attacks against civilians and civilian objects; the misuse of conventional, unconventional, and improvised weapons and weapon systems; industrial-grade custodial abuses exemplified by photographs secreted from the country in 2013 by a former forensic photographer codenamed “Caesar”; the denial of humanitarian aid and what appears to be the deliberate use of starvation as a weapon of war; the intentional destruction of cultural property; and rampant sexual violence against men, women, and children. The emergence of the Islamic State of Iraq and the Levant (ISIL) on the scene introduced a new set of even more ruthless perpetrators that have brought the violence to a new even more disquieting level of brutality. In addition to war crimes, the Syrian people have experienced other crimes under international criminal law, including crimes against humanity, torture, terrorism, and potentially genocide against ethno-religious minorities.

These extreme levels of violence, coupled with the lack of any apparent progress until very recently toward finding a political resolution to the various disputes in Syria, have generated a massive refugee crisis in the region and beyond. More than 4.5 million people (out of a population of 22 million) have fled across Syria’s borders, more than 7 million are internally displaced, and half the population needs humanitarian assistance in the form of food and/or shelter. The situation — described last year by Director of National Intelligence James Clapper as an “apocalyptic disaster” — remains grave and continues to deteriorate, without an endpoint in sight.

Although almost every war crime known to humankind has been committed in Syria, this set of posts will focus on some open legal and factual issues around certain war crimes that are particularly salient in the Syrian conflict. My legal guideposts will be the Statute of the International Criminal Court (ICC) and the ICRC’s monumental customary international law (CIL) study. The latter is particularly relevant since national penal codes and the ICC Statute do not codify all war crimes, particularly when it comes to those committed in non-international armed conflicts (i.e., conflicts between states and non-state actors, or NIACs). Indeed, if there is ever an international, regional, hybrid, or domestic tribunal with jurisdiction over events in Syria, prosecutors could conceivably charge a range of war crimes that might not be readily prosecutable before the ICC, including many crimes that have been under-theorized and rarely prosecuted.

Below, I walk through when an “armed conflict” began (as defined by international law), and map out what the law governs war crimes committed in the country. The law of armed conflict — or international humanitarian law (IHL) — is highly technical. It is found in disparate treaties and in customary international law (i.e., state practice coupled with a sense of legal obligation). As a result, carefully laying out which treaties and customary norms apply will enable a determination of which war crimes can be prosecuted, which tribunals might have jurisdiction, and which perpetrators are subject to charges. In subsequent posts, I will offer more of a “deep dive” into particular war crimes being committed, particularly those that have been under-theorized or -prosecuted.

The Existence of an Armed Conflict and Applicability of International Humanitarian Law

There is no definitive date for the initiation of the armed conflict within Syria. This matters because the commission of war crimes requires the existence of an armed conflict, though other international crimes (e.g., crimes against humanity, genocide) do not. Under international law, an armed conflict is distinct from sporadic or minor acts of violence, including riots, banditry, ordinary crimes, and isolated acts of terrorism. Announcing a standard that has generally enjoyed consensus, with some notable exceptions, the International Criminal Tribunal for the former Yugoslavia (ICTY) stated in Tadić (para. 70) that an armed conflict exists when there is “protracted armed violence between governmental authorities and organized armed groups or between such groups within a State.” This standard contains two key criteria: the intensity of the fighting and the degree of organization of the parties as measured in part by their operating under responsible command. Situations that do not meet these criteria are governed exclusively by other bodies of law, including domestic law and human rights law, which generally impose more stringent requirements for the use of force and stronger human rights protections.

Starting in March 2011, the Syrian government began deploying deadly force against peaceful protesters. The violence remained asymmetrical, however, until later that spring and early summer when an organized armed opposition, made up of Syrian army defectors and rebels drawn from the civilian ranks, began to coalesce and engage government forces. The Free Syrian Army, which announced itself in July 2011, created a Supreme Joint Military Command of the Syrian Revolution in an effort to unify and coordinate the operations of the various insurgent armed groups on the ground and to improve communications with the nascent political opposition. The International Committee of the Red Cross (ICRC) seemed to assume the existence of an armed conflict in May 2012 and publicly confirmed the conflict’s initiation in an operational update in July 2012. Being unable to verify first the intensity of the violence, and then the degree of organization of the FSA or its associated groups, the Independent International Commission of Inquiry on the Syrian Arab Republic (COI) evaluated the situation in Syria under human rights law until its third report, released in August 2012. At that time, the COI clearly stated that a NIAC existed and that the application of IHL was appropriate (para. 12).

The COI went on to say that the IHL threshold was crossed, in its estimation, as early as February 2012 (Annex II, paras. 2–3). An expert assessment released by Chatham House set the inflection point at March 2012; Human Rights Watch concluded that war crimes were being committed in April 2012. It is the existence of an armed conflict that triggers the applicability of IHL and with it, the war crimes prohibitions.

Conflict Classification

There is little treaty law — as distinct from CIL — governing the commission of war crimes in Syria, and what law does exist requires an understanding of the type of underlying conflict. The foundational treaties devoted to regulating the means and methods of warfare, the 1899 and 1907 Hague Conventions, apply only to international armed conflicts (i.e., those between states, or IACs) and do not contain penal provisions. The 1949 Geneva Conventions (designating so-called grave breaches that are subject to universal criminal jurisdiction) protect certain vulnerable classes of person — such as civilians and prisoners of war — but they also apply only to IACs.

Only common Article 3 of those treaties, which does not designate its list of prohibitions as crimes per se, governs all non-international armed conflicts (NIACs). Syria has not ratified Protocol II to the Geneva Conventions, which amplifies the treaty law governing certain NIACs that involve violence between governmental forces and armed non-state actors (but not necessarily violence between different non-state actors) and some showing of territorial control by rebel forces. Protocol I to the Geneva Conventions — which Syria has ratified — melds the Geneva Conventions’ grave breaches regime with Hague Conventions’ rules on means and methods, but it too applies only to IACs. Protocol I considers an IAC to include conflicts where people are fighting to exercise their right of self-determination against colonial powers and “racist regimes.” Although some opposition movements have in the past agreed to be bound by Protocol I via declarations issued under Article 96(3), this idiosyncratic standard has rarely, if ever, been formally applied in practice and may or may not encompass armed conflicts — like the one in Syria — fought to unseat an authoritarian regime.

The Syrian conflict — really a web of conflicts — by and large implicates the law governing NIACs. (One exception is the long-time occupation of the Golan Heights, which remains governed by the Fourth Geneva Convention.) In terms of conflict classification, it is possible to identify several overlapping NIACs: conflicts pitting the Assad regime against non-state opposition groups; the conflict between the Assad regime and al-Qaeda-affiliates such as the al Nusra Front; conflicts between opposition groups; and the conflict involving ISIL/Daesh against all of the above. To be sure, the assorted non-state actors enjoy varying degrees of lethal and non-lethal support (e.g., funding, technical assistance, train-and-equip aid, provision of weaponry) from a range of states — including the United States, the Gulf States, Jordan, France, Turkey, the United Kingdom, etc. (All the while, Russia, Iran, and Hezbollah have backed the Assad regime.)

However, absent a higher level of involvement in some form — i.e., open intervention by these states on the side of the opposition, higher degrees of control over one or more non-state armed groups, or the recognition of an opposition government — it is not clear that the levels and degree of external support are sufficient to cross the “internationalization” threshold that is necessary to trigger the full application of the Geneva Conventions. In its final judgement in Tadić (at para. 137), the ICTY Appeals Chamber established a standard of “overall control” to internationalize a conflict between a state and a non-state armed group. It wrote that an outside state must have a role in “organising, co-ordinating or planning the military actions” of the non-state group to render the conflict an international one. As states increase their support of armed non-state actors in Syria embattled with the regime, one or more of these NIACs may become sufficiently “international” to trigger the Conventions’ clearer rules and penal regime.

It is worth pausing for a moment to acknowledge that a number of states have deployed armed force on the territory of Syria without its overt consent. This includes an early Israeli airstrike on a convoy apparently carrying anti-aircraft weapons and bound for Hezbollah in Lebanon in January 2013; United States-led strikes starting in September 2014 (and eventually involving Australia, Bahrain, Canada, France, Jordan, Saudi Arabia, Turkey, United Arab Emirates, and the United Kingdom) as part of the Combined Joint Task Force’s Operation Inherent Resolve against ISIL; and the intensified French strikes following the terror attacks in Paris in November 2015. (Jonathan Horowitz mapped these strikes here and here.) But these operations are not engaging Syrian regime forces directly. Indeed, many have occurred in areas outside of the effective control of the Syrian government. Nonetheless, ever since Israel’s military operation in 2006 in response to Hezbollah attacks emanating from Lebanon, some commentators have characterized this dynamic — the forces of one state engaged in conflict with a non-state armed group on the territory of another state without the latter’s consent — to rise to the level of an IAC.

This view, however, is not universally held. The ICRC’s commentary to Article 2 of the Geneva Conventions indicates that an IAC exists only if two states are directly engaged in conflict. That said, the commentary sets quite a low threshold: It states that “[a]ny difference arising between two States and leading to the intervention of armed forces” is sufficient and that it “makes no difference how long the conflict lasts, or how much slaughter takes place.” The ICRC commentary on Article 1 of Additional Protocol I is in accord, indicating that IHL “covers any dispute between two States involving the use of their armed forces,” regardless of the length or intensity of the fighting. (State practice and many commentators, on the other hand, suggest that a higher intensity threshold of inter-state hostilities must be met before an IAC would exist and IHL would apply.)

The Customary International Law Governing Non-International Armed Conflicts

Although conflict classification remains an important exercise, it has become less relevant for the prosecution of war crimes in recent years. Customary international law now prohibits and penalizes many breaches of IHL, even those first articulated in treaties without a penal regime, regardless of whether they are committed in an IAC or a NIAC. Thus, although the Hague Conventions, common Article 3, and Additional Protocol II contain no express war crimes provisions, many violations of their terms now give rise to individual criminal responsibility as a matter of CIL regardless of the type of conflict. As such, a tribunal dedicated to the conflict in Syria (and/or Iraq) could prosecute most war crimes without running afoul of the principle of legality in international law. This principle embodies the ex post facto prohibition found in US constitutional law and prohibits the prosecution of anyone for an act that was not criminal at the time it was committed.

The ICC Statute drafters incorporated much (but not all) of the operative CIL governing war crimes committed in IACs and NIACs into Article 8 of the ICC Statute, which invites the prosecution of (a) grave breaches of the Geneva Conventions; (b) serious violations of common Article 3 committed against persons taking no active part in the hostilities; and (c) other serious violations of the laws and customs of war that are applicable in IACs and NIACs. The provisions depart slightly from Protocol II’s scope and apply to situations in which “there is protracted armed conflict” between a state and non-state groups (or between non-state groups) without requiring a showing of territorial control. All that said, the ICC Statute’s provisions on war crimes are more extensive for IACs as compared to NIACs. As such, if an ICC referral is ever forthcoming, conflict classification will remain relevant with respect to certain war crimes, including some that are quite salient in the Syrian conflict. It is important to note that Syria has not ratified the ICC Statute; as such, the ICC could assert jurisdiction over war crimes committed in Syria only for acts committed by nationals of states party. This includes foreign fighters from the United Kingdom and other ICC member states, as Jennifer Trahan has discussed.) Likewise, if the only courts available to prosecute war crimes in Syria are domestic courts, conflict classification may be relevant, since individual states may not have codified all war crimes with respect to the full range of conflicts (see this study by American University’s War Crimes Research Office for details).