[Editor’s Note: This article continues a Just Security series, Prosecuting the Crime of Aggression Against Ukraine. All articles in the series can be found here.]

Speaking yesterday in The Hague, Ukrainian President Volodymyr Zelenskyy called for accountability for the crime of aggression. After calling for a minute of silence “in memory of all those whose lives were taken by Russia, by its terror,” he proclaimed, “Only one Russian crime led to all of these crimes. This is a crime of aggression. The start of evil, the primary crime. There should be responsibility for this crime! And it can only be enforced by the Tribunal.” That same day, Zelenskyy declared that Ukraine opposes “hybrid” formats for such a court: “We will work without any hybrid formats, we will work on a specific tribunal to ensure accountability for their crimes, murders, and torture. We understand who gave the orders. These people must not be untouchable. This is very important for us, this is one of the fundamental issues.”

As previous entries in this series have explained at some length, there is currently no international court with jurisdiction to try the crime of aggression in Ukraine. While there is widespread support for closing this accountability gap, there is significant disagreement as to how to do that. Zelenskyy’s announcement yesterday places him at odds with the Biden administration, which has endorsed a court “rooted in Ukraine’s judicial system, but that also includes international elements”—precisely the kind of “hybrid” court Zelenskyy has now outright rejected.  Among other shortcomings, such a hybrid approach would not be able to indict Putin as long as he remains in office.  That makes the approach a non-starter for Ukrainians.

Zelenskyy instead supports creating a court pursuant to a United Nations General Assembly resolution requesting the Secretary-General negotiate an agreement with the government of Ukraine to create a Special Tribunal, an approach that also has supporters in the U.S. Congress. But some have asked whether that approach is possible—can an international tribunal to try the crime of aggression be established by the U.N. without the involvement of the Security Council? As this article will explain, there is ample reason to conclude that it can.

The U.N. Charter

Let’s begin with the U.N. Charter. Both the General Assembly and the Security Council are responsible for the core mission of the Charter – that is, in the maintenance of international peace and security. The Charter makes clear that, under Chapter VII of the Charter, the Security Council has exclusive authority to authorize military interventions. It also has exclusive authority, under Article 48, to authorize enforcement measures and to compel members of the U.N. to take actions that it determines are required for the maintenance of international peace and security. But this leaves a significant role for the General Assembly.

Article 1 of the Charter sets out the purposes of the U.N., including, first:

To maintain international peace and security, and to that end: to take effective collective measures for the prevention and removal of threats to the peace, and for the suppression of acts of aggression or other breaches of the peace, and to bring about by peaceful means, and in conformity with the principles of justice and international law, adjustment or settlement of international disputes or situations which might lead to a breach of the peace.

Article 2(2), moreover, establishes an obligation for all Member States, as one of the principles of the U.N., to “fulfill in good faith the obligations assumed by them in accordance with the present Charter.”

The purpose of maintaining international peace and security appears throughout the Charter and influences the interpretation of other articles. For example, Article 2 stipulates principles by which the Organization and member states must abide in pursuit of the purpose of the U.N., most notably including the prohibition on the threat of or use of force. Many of the powers available to the General Assembly and the Security Council are premised on the organs’ duty to prevent or respond to breaches or threats to international peace and security. It follows from the terms of the Charter and the customary law of treaties that member states must refrain from acts that frustrate the Charter’s raison d’etre, namely, the maintenance of international peace and security.

The crime of aggression, “the supreme international crime,” is in the postwar era defined in reference to the U.N. Charter. Article 2(4) provides, “All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any State, or in any other manner inconsistent with the Purposes of the United Nations.” Hence there is little question that the creation of a special tribunal to try the crime of aggression – to hold those responsible for the violation of this foundational principle of the Charter – is critical to upholding one of the core purposes of the U.N., as well as the “object and purpose” of the Charter, as understood under the Vienna Convention on the Law of Treaties.

Article 10 empowers the General Assembly to “discuss any matters within the scope of the present Charter or relating to the powers and functions of any organs provided for in the present charter” and to “make recommendations” to either the General Assembly or the Security Council on such matters. This article grants the General Assembly the authority to consider what measures may be taken to counter a threat to international peace and security, particularly in instances where the Security Council fails to act. Indeed, Article 10 was widely considered the primary basis in the creation of the Uniting for Peace Resolution, which provides that “if the Security Council, because of lack of unanimity of the permanent members, fails to exercise its primary responsibility for the maintenance of international peace and security in any case where there appears to be a threat to the peace, breach of the peace, or act of aggression, the General Assembly shall consider the matter immediately with a view to making appropriate recommendations to Members for collective measures.” Article 10 was also invoked in the recent Liechtenstein veto reform initiative, which provides that any time a permanent member of the Security Council vetoes a resolution, that resolution will be automatically referred to the General Assembly within 10 working days so that the Assembly can hold a debate on the situation.

Article 11 empowers the General Assembly to consider, discuss, and make recommendations with regard to both general principles of cooperation in the maintenance of international peace and security, or any questions relating to the maintenance of international peace and security before it. Subsection (2) provides that “[a]ny such question on which action is necessary” must be referred to the Security Council. The International Court of Justice (ICJ) in the Certain Expenses case interpreted this provision to mean only that General Assembly may not undertake coercive or enforcement actions. It is widely agreed, for example, that the General Assembly is within its power to call upon members to impose sanctions as a collective measure against offending states. Indeed, in the Certain Expenses case, the ICJ also upheld the competence of the General Assembly under this article to establish a voluntary peacekeeping force, though it was careful to note that only the Security Council may “order coercive action.”

Article 24 indicates that Member States “confer on the Security Council primary responsibility for the maintenance of international peace and security, and agree that in carrying out its duties under this responsibility the Security Council acts on their behalf.” In using the word “primary,” Article 24 of the U.N. Charter implicitly acknowledges that the General Assembly is a residual insurer of the object and purpose of the Charter. That interpretation was confirmed by the ICJ in the Certain Expenses case, in which the Court held that the Security Council maintains primary—but not exclusive—responsibility over peace and security, particularly in light of its Chapter VII powers, because “[t]he Charter makes it abundantly clear … that the General Assembly is also to be concerned with international peace and security.” The ICJ reaffirmed the Security Council’s primary, but not exclusive, responsibility for the maintenance of international peace and security in its Wall Advisory Opinion.

Last, while the General Assembly resolution would “request” the Secretary-General negotiate an agreement with the government of Ukraine to create a Special Tribunal for the Crime of Aggression, such requests are understood to create an obligation on the Secretary-General to act. Under Article 98 of the U.N. Charter, the Secretary-General “shall perform such other functions as are entrusted to him” by the General Assembly.

Historical Practice

Turning next to historical practice: While there is no perfect analog, there is substantial practice that suggests that a Special Tribunal to try the Crime of Aggression can be created through an agreement between the U.N. and Ukraine, pursuant to a resolution of the General Assembly. Here we discuss several examples of prior General Assembly action that offer insight into the organ’s authority as it has been exercised to date. It is important to note at the outset that such a tribunal would not be able to order coercive measures on any non-consenting state – for example, it could not compel them to carry out arrests of those it indicts. It could, however, accept the voluntary assistance of member states in carrying out its mission.

United Nations Administrative Tribunal & Internal Justice System (1949)

The United Nations Administrative Tribunal (UNAT) was established by the General Assembly through passage of a Resolution in 1949. The tribunal was an independent organ that could hear and judge internal administrative matters, such as employment contract disputes. Though the Tribunal no longer operates, its successor does: In a series of resolutions beginning in 2007, the General Assembly replaced the Tribunal with a two-tier International Justice System. That system “provides an internal system of justice for all UN system staff” and has the power to resolve disputes both formally and informally.

In a 1954 Advisory Opinion, Effect of Awards of Compensation Made by the United Nations Administrative Tribunal, the ICJ considered the legality of the Tribunal, which it described as “an independent and truly judicial body pronouncing judgments without appeal within the limited field of its functions.” As it observed, “[t]he legal power of the General Assembly to establish a tribunal competent to render judgements binding on the United Nations has been challenged. Accordingly, it is necessary to consider whether the General Assembly has been given this power by the Charter.”

The Court began by observing that there was “no express provision for the establishment of judicial bodies or organs and no indication to the contrary.” But that silence was not the end of the story. The Court noted that it had earlier determined that, “[u]nder international law, the Organization must be deemed to have those powers which, though not expressly provided in the Charter, are conferred upon it by necessary implication as being essential to the performance of its duties.” The Court went on to note that, among other things, the Secretary-General is “the chief administrative officer of the Organization.” It was “inevitable,” the Court noted, “that there would be disputes between the Organization and staff members as to their rights and duties.” And while the Charter does not authorize any of the U.N. organs to adjudicate these disputes, it would “hardly be consistent with the expressed aim of the Charter to promote freedom and justice for individuals and with the constant preoccupation of the United Nations Organization to promote this aim that it should afford no judicial or arbitral remedy to its own staff for the settlement of any disputes which may arise between it and them.” It thus concluded that the power to establish a tribunal that could resolve such disputes “arises by necessary intendment out of the Charter.”

Special Court for Sierra Leone (2000)

The Special Court for Sierra Leone (SCSL) was created by Secretary-General based on a request by Security Council acting under Chapter VI, not Chapter VII. In Resolution 1315, the Security Council requested that the Secretary-General negotiate with the Government of Sierra Leone to establish an independent special court. Because the Security Council did not act under Chapter VII (and because the Court was created by agreement between the U.N. and Sierra Leone, and not other states), the SCSL was unable to require non-consenting states to execute its arrest warrants. Nonetheless, the tribunal was properly characterized as an “international” court and thus empowered to set aside personal immunities. Indeed, the SCSL Appeals Chamber specifically found that a sitting head of state of a foreign state that was not party to the agreement between Sierra Leone and the U.N. – Liberian President Charles Taylor – was subject to prosecution in the court for crimes committed in Sierra Leone and could not rely on personal immunities to avoid indictment. In making this finding, the Appeals Chamber emphasized that when the U.N. Security Council called for the establishment of the court, it was acting on behalf of all U.N. Members and, thus, the agreement giving rise to the court was “an agreement between all members of the UN and Sierra Leone”—making it “truly international.”

This precedent offers at least two important lessons: First, Chapter VII authority is not essential to creation of an international criminal tribunal, as the Security Council acted under Chapter VI in creating the SCSL (and thus was not exercising coercive authority). Second, a tribunal created through an agreement negotiated by the Secretary-General on behalf of the United Nations and a member state can constitute an “international tribunal” for purposes of personal immunities with regard to the head of state of a non-consenting state. In the case of the SCSL, that negotiation took place pursuant to a request in a resolution of the Security Council acting under Chapter VI; a resolution of the General Assembly would arguably have at least as strong a claim to represent the membership of the U.N.

Extraordinary Chambers in the Courts of Cambodia (2003)

The General Assembly gave rise to the Extraordinary Chambers in the Courts of Cambodia (ECCC). Cambodia approached the United Nations, requesting “assistance of the United Nations and the international community in bringing to justice those persons responsible for the genocide and crimes against humanity during the rule of the Khmer Rouge.” General Assembly Resolution 52/135 then requested that the Secretary-General establish a Group of Experts for Cambodia, which recommended that “the United Nations should establish an ad hoc international tribunal to try Khmer Rouge officials for crimes against humanity and genocide . . . that the Security Council establish this tribunal under Chapter VI or VII of the Charter of the United Nations, or, should it not do so, that the General Assembly establish it.” Cambodia instead decided on an alternative approach—the creation of a tribunal within the Cambodian legal system. In Assembly Resolution 57/228, the General Assembly requested the Secretary-General negotiate with Cambodia an agreement creating the Extraordinary Chambers and regulating the cooperation between the U.N. and Cambodia. While the ECCC is located within the Cambodian court system, it provides clear evidence that the General Assembly can contribute to the establishment of a treaty-based tribunal.

International, Impartial and Independent Mechanism (Syria) (2017)

In 2016, the Assembly responded to a Security Council deadlock (caused by Russia’s veto) in the face of evidence of Syrian atrocities through the adoption of Resolution 71/248, establishing the International, Impartial and Independent Mechanism to Assist in the Investigation and Prosecution of Those Responsible for the most Serious Crimes under International Law Committed in the Syrian Arab Republic since March 2011 (the “IIIM”).

During debate and in a note-verbale, dated Feb. 8, 2017, Russia complained that “the General Assembly acted ultra vires—going beyond its powers as specified in . . . the Charter of the United Nations.” It claimed that the mechanism vested powers that were prosecutorial in nature and that “prosecutions, criminal investigations and support of criminal investigations are not among the functions of the General Assembly. It cannot create an organ that has more powers than the Assembly itself.” General Assembly debate and voting records show that UN members were not persuaded by this argument. Supporting members reaffirmed that the purpose of the mechanism (which was, unlike the ECCC and SCSL, created over the territorial state’s objection), was not to prosecute, but to “facilitate and expedite criminal proceedings, without prejudice to where and when such proceedings will take place.” Underpinning discussions about the mechanism was Member States’ explicit sense of urgency for the General Assembly to take action in response to the gridlock in the Security Council, which was blocking the Council from fulfilling its mandate to maintain international peace and security. The creation of the IIIM was viewed as a key step to preserve evidence and signal Members’ non-tolerance of impunity, which may account for the speed with which the Resolution advanced through the drafting and consultation process and went into operation.

The Jurisdiction of a Special Tribunal for the Crime of Aggression

The Charter, together with the historical examples, demonstrate that General Assembly has the authority to request that the Secretary-General enter an agreement with Ukraine to establish a Special Tribunal for the Crime of Aggression. But there is a further question as to the source of the court’s jurisdiction, given the General Assembly’s lack of enforcement powers.

The new Special Tribunal could be conferred international criminal jurisdiction over the crime of aggression in two ways. First, as with the courts formed for Sierra Leone and Cambodia (and unlike the IIIM), where the territorial state consents through entering into an international agreement with the United Nations, it vests the tribunal with a jurisdictional title. Second, because the crime of aggression is rooted in customary international law and the prohibition of aggression is a jus cogens norm, there is a strong case that there is an existing international jurisdiction that need only be activated. This international criminal jurisdiction—“rooted in the international community as a whole”—can be activated when an international tribunal acquires it through a specific instrument, like a negotiated agreement between the U.N. and a member State. Under either approach cases, the U.N. General Assembly would not vest the special tribunal with jurisdiction, “it would,” as an earlier Just security article explained, “only help activat[e] the proper international exercise of an already existing jurisdiction.”

Both the SCSL and the ECCC took the first approach: the consent of the territorial state formed the basis for the court’s jurisdiction. The Security Council acting under Chapter VI and the General Assembly, respectively, acted to activate the exercise of existing jurisdiction. The same approach could be utilized by the Special Tribunal. Ukraine is, after all, one of the territorial States of the crime as the victim of Russia’s aggression and possesses a jurisdiction title that it can confer to an international tribunal for the purpose of adjudication.

The capacity of such a Tribunal is not limited to the capacity of the consenting state, here Ukraine, to try the crime in its own domestic courts. An international Tribunal created by a negotiated agreement between the Secretary-General and a consenting state to try a crime under international law creates a court with an international character. That, in turn, allows the court to set aside personal immunities that would restrict prosecutions in foreign domestic courts, including the courts of the consenting state. This was true of the SCSL, which could indict a sitting foreign head of state even though Sierra Leone’s own domestic courts would have been barred from acting by personal immunity. This same principle animates the ICC. The ICC is not limited by personal immunities and thus exercises greater authority than is possessed by the individual states whose consent is the basis for the court’s jurisdiction. In a recent Just Security article, Leila Sadat defends what she terms this “collective conferral” authority. It is precisely this authority that allows the ICC to indict Putin – the head of state of a non-state party who would otherwise be immune from prosecution.


Viewing the law and history together paint a clear picture: First, the Charter’s central purpose is the maintenance of international peace and security, and, where the Security Council is unable to act, the General Assembly possesses subsidiary powers to uphold this core purpose. Second, the General Assembly is capable of passing a Resolution that leads to the creation of a body with a decidedly judicial character. Third, the U.N. General Assembly has the authority to request the Secretary-General act to establish a Special Tribunal that would allow the exercise of an existing jurisdiction—and the Secretary General would be obligated to take steps to carry out that request. That court, in turn, would have an international character and thus would not be required to observe personal immunities for an international crime even though the consenting state’s own courts would be.

In sum, it is clear that General Assembly is empowered to request that the Secretary-General conclude a treaty with Ukraine to establish a Special Tribunal to try the crime of aggression committed in and against Ukraine.

IMAGE: United Nations Secretary General Antonio Guterres speaks during the 77th session of the United Nations General Assembly (UNGA) at the U.N. headquarters on September 20, 2022 in New York City. Photo by Anna Moneymaker/Getty Images)