By Christian Wenaweser and Sina Alavi[1]
Background and Early Discussions
We started discussing the idea of creating a Special Tribunal for the Crime of Aggression against Ukraine (“Special Tribunal” or “STCA”) in the immediate aftermath of Russia’s full-scale invasion on February 24, 2022. At the time, we were both working at the Permanent Mission of Liechtenstein to the United Nations. For Liechtenstein—a small State whose security and prosperity depend on a strong international legal order—supporting and strengthening international criminal justice has long been a cornerstone of its foreign policy.[2] When we first began discussing the idea in those early days, it was natural for us to draw directly on our past experiences: Liechtenstein had made accountability for the crime of aggression a central focus of its engagement at the International Criminal Court (ICC), with one of us serving as President of the ICC’s Assembly of States Parties at the 2010 Kampala Review Conference, which adopted the amendments to the Rome Statute that defined the crime of aggression and set the conditions for the ICC’s jurisdiction for that crime.[3] More recently, Liechtenstein initiated the UN General Assembly (UNGA) resolution creating the International, Impartial and Independent Mechanism (IIIM) for Syria, after Russia and Chinahad vetoed a referral of the situation to the ICC. The creation of the IIIM was considered a novel step to secure justice and accountability in the future for the Syrian people.[4]
In Ukraine, the contradiction was even starker: Russia, again wielding its permanent seat, had been not only the main obstacle to accountability but also the aggressor itself—shattering another UN Member State’s sovereignty and territorial integrity in direct defiance of the Security Council’s core mandate to safeguard international peace and security. Two long-standing priorities shaped Liechtenstein’s response to Russia’s full-scale invasion of Ukraine: (1) building international justice mechanisms capable of addressing acts of aggression at the leadership level, and (2) strengthening the role of the General Assembly when the Security Council is paralyzed or suffers from a dereliction of duty.
During the first days after the invasion, calls for accountability for the crime of aggression against Ukraine arose from multiple directions, as the brazenness of Russia’s actions made the crime committed by its leadership impossible to ignore. Ukrainian representatives themselves called for a tribunal as early as March 4, 2022,[5] and scholars and diplomats followed suit, including Philippe Sands who, in the Financial Times, made one of the first public calls in a widely read media outlet.[6] This widespread outcry reflected an early, shared recognition among legal scholars, diplomats, and policymakers that Russia’s actions demanded a response mechanism beyond the existing international justice framework,
Following referrals from 39 of its States Parties, the ICC Prosecutor moved quickly to open investigations into alleged war crimes and crimes against humanity flowing from the Russian aggression.[7] However, the ICC lacked jurisdiction to investigate and prosecute the crime of aggression itself, due to the limitations built into the Kampala Amendments to the Rome Statute—limitations that few were as aware of as us, given Liechtenstein’s aforementioned leading role in the Kampala Review Conference (a meeting of ICC States Parties held in Uganda in 2010) and in securing the adoption of the amendments that introduced a definition of the crime into the Rome Statute.
Although Ukraine had accepted the ICC’s jurisdiction on an ad hoc basis as early as 2014 and subsequently ratified both the Rome Statute and its Kampala Amendments in June 2024, these steps could not confer jurisdiction over crimes of aggression committed by nationals of non-State Parties—such as the Russian Federation.[8]This limitation reflects the political compromise underlying the Kampala Amendments and explains why the Court was able to issue arrest warrants for Russian officials, including President Putin, for other crimes within its jurisdiction.[9]
While the accountability gap was glaring, committing to the effort to create a Special Tribunal was neither a quick nor an easy decision. There were two main reasons for hesitation. First, we anticipated that the strong consensus that had formed in the UN General Assembly around diplomatic measures against the aggression against Ukraine would not necessarily extend to the idea of a Special Tribunal—and that some of the States critical to providing military support to Ukraine would likely be among the skeptics. This skepticism, in turn, would have a chilling effect on the reaction of the UN membership as a whole. Second, though less weighty, there was the concern that establishing a Special Tribunal might be perceived as undermining the ICC and weakening the promise made at the time of the creation of the ICC in 1998 that establishing a permanent international criminal court would render the creation of special courts unnecessary. Ultimately, however, we concluded that allowing this brazen act of aggression to go unaddressed in an international court would be far more detrimental to the ICC by reinforcing the perception that the crime of aggression could not be prosecuted in practice.
This accountability gap quickly spurred academic and diplomatic debate. One of the earliest and most influential discussions took place in June 2022 at the Yale Club in New York, co-convened by Latvia, Liechtenstein, and Ukraine. At this closed-door roundtable, like-minded diplomats, legal scholars, and human rights advocates debated the feasibility and desirability of a Special Tribunal. The consensus that emerged from that meeting was that an international tribunal could be legally created through an UNGA resolution. Such a tribunal could be modeled on precedents like the Special Court for Sierra Leone (SCSL), established through a Chapter VI resolution of the UN Security Council, and the Extraordinary Chambers in the Courts of Cambodia (ECCC), created by UNGA resolution.
While this UNGA-based model was considered legally sound, especially as a means of addressing the personal immunities of high-level officials for this leadership crime, it was recognized early on that this approach would face significant political obstacles. Notably, some of Ukraine’s most important suppliers of military support were likely hesitant to support such an initiative. The UNGA’s strong resolutions condemning Russia’s aggression—adopted under the Uniting for Peace formula[10]—owed their success largely to a coordinated lobbying campaign by the G7 and the European Union, a dynamic that was unlikely to be replicated in efforts to establish a Special Tribunal through the UNGA.[11] As a result, it was not guaranteed that the creation of a Special Tribunal could count on the required political support in the General Assembly.
Over the course of the ensuing discussions, it became increasingly evident that political considerations—particularly the support of G7 States—would define the parameters of what was politically achievable. At the same time, the positions taken by some major States from the Global South in relation to Russia’s aggression also raised challenges for maintaining principled consistency in upholding international law. These positions were not monolithic, and were often justified by reference to concerns about selective enforcement of international law, traditions of non-alignment, or economic and strategic dependencies—considerations that complicate, but do not resolve, the tension between neutrality and the prohibition of aggression. For example, on several occasions, larger Global South States chose abstention or remained silent in UN proceedings in response to Russia’s aggression, framing these decisions as strategic “neutrality.”[12] This dynamic reflects a broader shift in the global landscape of international law, in which the most consistent champions of an international order based on the rule of law are increasingly medium and smaller States—often outside both the G7 and BRICS—whose security and prosperity depend most directly on the protection and predictability afforded by international law.[13]
With that background, this Essay will analyze the agreement to establish the Special Tribunal through two main lenses: how sound it is in legal terms and how well it works politically. Success here cannot be about achieving perfect legal theory. Rather, it should be defined by striking a workable balance between four things: (1) legitimacy under international law, (2) political feasibility in a divided world, (3) practical and symbolic value in addressing aggression as a leadership crime, and (4) strengthening rather than splintering the broader system of international justice. While all these considerations are essential, the overriding concern must be the question of impact on the future development of public international law. Viewed from this vantage point, the analysis of the final outcome is therefore complex.
The Push to Launch a “Core Group”
In the latter half of 2022, momentum gathered for the creation of a Special International Tribunal, particularly among States in Ukraine’s neighborhood and advocates of a strong international legal order. These States showed willingness to move forward on the creation of a Special Tribunal, with the understanding that leadership of the project should be with Ukraine itself. One proposed initiative involved drafting a General Assembly resolution to mandate the creation of an ad hoc aggression tribunal. Though elements for a possible resolution were drafted, they were never formally circulated. Still, it served to focus attention and affirmed that such a tribunal could advance the goals of justice and lasting peace.[14]
In parallel, legal scholars and experts proposed various institutional models. While there was strong legal support for a UNGA-based tribunal, many remained skeptical about the political feasibility of such a move. Complicating matters further, ICC Prosecutor Karim Khan publicly expressed skepticism toward the initiative, cautioning that it might dilute the ICC’s relevance; his reasons for this position remained unclear.[15] Instead, he urged States to focus on strengthening the ICC by expanding its jurisdiction over the crime of aggression, which to those involved in the discussions was clearly not an option for Ukraine given the timeframe required for such an approach gaps for aggression. The Prosecutor’s remarks caused diplomatic friction, particularly with Ukraine, and were used as an argument by States that were reluctant to engage in any effort to create a Special Tribunal.
Nevertheless, proponents of the Special Tribunal maintained that the ICC’s jurisdictional constraints necessitated two complementary initiatives: the creation of a Special International Tribunal for the aggression against Ukraine and the harmonization of the Rome Statute’s jurisdiction over all four of its core crimes for any future aggression. The Special Tribunal was never meant to undermine the ICC; rather it aimed to fill a legal void until broader reforms to harmonize the ICC’s jurisdiction took effect—in fact underlining the importance of the ICC’s jurisdiction over the crime of aggression. This is why Liechtenstein, from the outset of discussions on the Special Tribunal, called for a parallel and sustained effort to harmonize the ICC’s jurisdiction over the crime of aggression and thus to allow the Court to also exercise accountability for aggression committed by nationals of non-States Parties. These parallel efforts, we thought, were essential in light of the most brazen act of aggression since the creation of the United Nations.If Russia’s aggression, aimed at territorial conquest, were to be left without accountability, this would risk normalizing a return to an era of acquisition of territory by force—an outcome the international legal order created by the UN Charter was expressly created to prevent.
The STCA, therefore, responds to a specific and temporally bounded jurisdictional gap—namely, the ICC’s inability, under its current Statute, to exercise jurisdiction over the crime of aggression in the Ukraine situation—while simultaneously reinforcing the normative centrality of the ICC as the only permanent international criminal court. The STCA does therefore not undermine the ICC; it operates as a transitional, gap-filling mechanism designed to preserve the integrity of the prohibition on aggression until the Rome Statute’s jurisdictional regime is brought into line with the Court’s other core crimes.A parallel effort thus soon emerged to amend the Rome Statute and bring its jurisdiction over the crime of aggression in line with its treatment of war crimes, crimes against humanity, and genocide. This proposal aligned with a mandatory review of the ICC’s Kampala Amendments on the Crime of Aggression scheduled for 2025.[16]
As public debate intensified, a coalition of States committed to creating a Special Tribunal—informally dubbed the “FAQ Group”—began preparing explanatory materials, including its namesake FAQ, to clarify legal questions and counter political misconceptions. Alongside them, international law scholars published an online series of essays endorsing a UNGA-created tribunal. From the outset, these advocates emphasized that Ukraine must lead the initiative.
As momentum built toward the establishment of a Special Tribunal, Ukraine finally coalesced this momentum into what became known as the “Core Group,” a coalition of States whose legal experts convened in person - fourteen times over the course of two years - to explore options for creating a tribunal on the crime of aggression. The Core Group functioned as both a diplomatic forum and a legal drafting body, meeting regularly from early 2023 onward. In parallel, the United States and several major EU member States advanced a parallel initiative: the creation of the International Centre for the Prosecution of the Crime of Aggression against Ukraine (ICPA), formally launched within Eurojust on July 3, 2023, shortly after the inception of the Core Group discussions earlier that year.[17] While the ICPA was presented as a complementary mechanism, some observers wondered whether it might be intended to redirect political energy and focus away from the push for a dedicated tribunal. Its precise added value within the broader accountability architecture remains a matter of discussion. The work of the ICPA was discussed in several convenings of the Core Group, butthe information shared with Core Group members was at times not satisfactory. In particular, it was unclear what definition of the crime of aggression the ICPA was applying, which resulted in a lack of transparency and understanding, as the ICPA could have simply used the Rome Statute definition. The relationship between the ICPA and the Special Tribunal still needs to be determined, but the general expectation is that the ICPA will be discontinued and its work made available to the Special Tribunal.
The Core Group and Key Legal-Political Debates
The Core Group ultimately expanded to encompass around forty States, alongside institutional stakeholders such as the European Union and the Council of Europe.[18] The group remained predominantly European in composition, with limited success in attracting participation from States outside the continent.[19]
Substantive discussions among Core Group members converged around six central legal and political issues: (1) the appropriate institutional venue for the tribunal, (2) the treatment of personal immunities, (3) the applicable definition of the crime of aggression, (4) the permissibility of trials in absentia, (5) the procedural mechanisms for initiating investigations, and (6) the tribunal’s legal scope and safeguards.
Venue
Early proposals focused on establishing the Special Tribunal via a resolution of the UNGA, as discussed at the Yale Club Roundtable. This model promised strong legitimacy and the legal capacity to override personal immunities of senior officials (the ‘Troika’—a term used in diplomatic shorthand to refer to the Head of State, Head of Government and Foreign Minister, as the three officials considered to hold ultimate decision-making authority over an act of aggression).[20] However, it also faced resistance from powerful global actors, including those participating in the Core Group, and a perceived lack of enthusiasm from many States of the Global South, as was anticipated during the Yale Club Roundtable discussions.
An alternative approach, favored mostly by G7 countries, suggested embedding an “internationalized” tribunal within Ukraine’s domestic legal system, drawing on precedents such as the Kosovo Specialist Chambers.[21] Yet this model faced constitutional barriers—Ukraine’s Constitution prohibits the establishment of specialized courts—and was viewed by many Core Group members as duplicative of ongoing domestic prosecutorial efforts and as lacking added value, while resulting in considerable financial cost. Its failure to address personal immunities further undermined support, as many Core Group members viewed this as a key objective of the STCA.[22]
The divergence between these two camps created a prolonged stalemate. In early 2024, a third model gained traction which had already been discussed in early stages of the work of the Core Group: establishing the tribunal under the auspices of the Council of Europe. This approach was initially met with skepticism, particularly regarding whether it could be sufficiently international in nature and, linked to this, its ability to address personal immunities. Some also expressed doubts about the likelihood of support for a regionally established Special Tribunal beyond Council of Europe members, especially considering limited response to the creation of the Register of Damages caused by the Russian aggression against Ukraine, nitiated by the UN General Assembly and also embedded in the Council of Europe.[23]
However, the model began to gain broader support following a special seminar held in Strasbourg in the spring of 2024, co-hosted by Liechtenstein, Ukraine, and the Council of Europe. The ongoing stalemate in the Core Group—in which neither of the previous two options was able to garner sufficient support—also pushed the Core Group toward this alternative.[24] The Council of Europe model presented a politically feasible path forward, anchored in an institution with a long-standing commitment to human rights and the rule of law. It offered a viable regional framework with credible political backing. Ultimately, the Core Group coalesced around this option as a pragmatic compromise between fully international and purely national approaches, with both camps of the view that this model was compatible with their interpretation of the immunities question.
Immunities
A central legal and political challenge was whether a tribunal not created under Chapter VII of the UN Charter could pierce the personal immunities of senior Russian officials, particularly the ‘Troika’. While precedents such as Nuremberg, the Special Court for Sierra Leone, and ICC jurisprudence, including the ICJ Arrest Warrant case, establish that international tribunals can override such immunities, G7 States expressed strong reservations in the Core Group meetings.[25] They questioned whether a UNGA-based tribunal or a regional mechanism could legally prosecute sitting heads of state, and they opposed setting a new precedent in this regard.
Members of the so-called FAQ Group and other like-minded States, alongside Ukrainian representatives, argued that a tribunal lacking authority to pursue leadership-level accountability would fundamentally undermine its purpose. Aggression is a leadership crime under international law, and public perception—especially in Ukraine—linked the crime directly to the Russian president. Ukrainian representatives and officials, including at the highest levels, consistently underscored that the tribunal’s ability to investigate and prosecute the top leadership was essential and in fact indispensable.[26]
As a compromise, the Core Group devised a solution permitting the future prosecutor to indict the Troika for aggression but requiring the tribunal to suspend proceedings until those individuals leave office. This compromise emerged after acrimonious discussions, under mounting time pressure, and was driven by Ukraine’s desire to bring negotiations to a conclusion. This framework did not restrict the prosecution of other senior officials[27] Though seen by many as falling short of actual justice, the arrangement represented the outer limit of political consensus within the Core Group, and ultimately the realization that the G7 States would not consent to a solution on immunities that could be detrimental to the positions they would take in other contexts, including in the emerging debates concerning the jurisdiction of the International Criminal Court.
The compromise on personal immunities embodies both the creativity and political will to bring the negotiations to a successful conclusion, after a lengthy and at times repetitive negotiating process – and the limits of the Special Tribunal. By allowing indictments against sitting leaders while suspending proceedings until they leave office, the tribunal affirms the principle of accountability without immediate enforcement obligations. This arrangement invites criticism that international justice remains symbolic rather than operative, and it does not meet the objective originally set by many members of the Core Group, including Liechtenstein. Yet indictments, even when not enforced, have normative power: they reaffirm that leadership responsibility for aggression is a matter of law, not politics. The precedent of Charles Taylor’s indictment while still President of Liberia and his eventual conviction as an ex-President suggests that indictments can evolve into concrete justice.
Definition of the Crime of Aggression
Although Article 8 bis of the Rome Statute defines the crime of aggression and is widely regarded as customary international law,[28] agreement on its incorporation into the Special Tribunal’s statute (“Statute”) was neither immediate nor easy. Most Core Group members had ratified the Kampala Amendments and favored inclusion of the Rome Statute definition. However, some States noted that they had participated in the Kampala Review Conference but had not ratified the amendment. They also argued that the overall number of ratifications had remained low. They therefore suggested that a more tailored definition, reflective of the Ukraine context and recent UNGA resolutions, would be preferable.
The FAQ Group States and their allies maintained that the Kampala definition enjoyed near-universal consensus, both in the negotiation phase (which included Russia as a full participant) and in the subsequent adoption during the Kampala Conference, where “Understandings” were added to assist in the practical application of the definition. They stressed that deviating from this definition could undermine the Rome Statute and thus the authority of the ICC and dilute the consistency of international law. They also emphasized that the Kampala Amendments, including their definition, were the most widely ratified set of amendments to the Rome.
The matter remained unresolved until the Brussels convening in February 2025, where a breakout group comprising three G7 States and three FAQ Group States, including Liechtenstein, reached agreement on incorporating Article 8 bis into the draft Statute, supplemented with contextual language specific to the aggression against Ukraine[29]. This language was adopted by the full Core Group without reopening debate in the final round of negotiations in Strasbourg.
Trials in Absentia
The possibility of conducting trials in absentia also proved divisive. A minority of Core Group members, particularly from civil law traditions, supported the idea as a necessary tool given the improbability of securing the appearance or surrender of Russian leaders. Ukraine, whose domestic legal system permits trials in absentia, also strongly advocated for their inclusion.
However, many States raised concerns about due process, the tribunal’s legitimacy, and negative experience in the context of the Special Tribunal for Lebanon. [30]The potential cost and optics of retrials in the event of later arrest also fed into hesitations. As discussions on immunities advanced, however, Core Group members began to look at trials in absentia differently, particularly as a way of closing the gap on the immunities question – as some argued it would be highly unlikely to achieve the arrest and surrender of any senior Russian officials while they are still in power. Ukraine itself became very adamant on including trials in absentia provisions at the time when it became clear that the Special Tribunal would not be given the power to fully pierce the personal immunities of the Troika. Trials in absentia, which were accepted reluctantly, were balanced out, however, by the Statute’s procedural safeguards—mandatory counsel, retrial rights upon surrender, and enhanced notice requirements—that seek to mitigate fairness concerns.[31]
Ultimately, Ukraine’s insistence prevailed in the final negotiations. The draft Statute permits trials in absentia, subject to these strict procedural safeguards. This outcome was an effort to balance legal realism with fair trial guarantees and the biggest substantive concession made to Ukraine. For members of the Core Group, there was no question in the final stage of the negotiations that this concession should be made to Ukraine, which made this the central point of its position in the final stage of negotiations
. In practice, financial considerations will play a role here as well, in particular with respect to the provision concerning retrials[32] and any future residual mechanism after the STCA has completed its core work, as those could generate unknown down the road costs for States joining the EPA of the STCA
Proprio Motu vs. Transfer of Proceedings
A particularly delicate design question concerned the conditions under which the Special Tribunal’s prosecutor could open an investigation. This question revolved around whether the prosecutor should be empowered to proceed proprio motu—on their own motion—or be restricted to acting only after receiving a formal transfer of proceedings from Ukraine. Granting the prosecutor such autonomous powers would have underscored prosecutorial independence, aligning with best practices in other international justice mechanisms, in particular the Rome Statute of the International Criminal Court. Proprio motu power was also viewed by many in the Core Group as an additional element for the creation of a truly international tribunal, as it would delink prosecutorial discretion from Ukraine’s national prosecutor’s office and not undermine its perception as independent and impartial. However, a few States feared that allowing independent action might weaken the appearance of national consent and control. Others warned that limiting the prosecutor to Ukrainian transfers could leave the tribunal hostage to political considerations in Kyiv and, in an extreme scenario, result in a costly but inactive tribunal[33].
Throughout the discussions, the “transfer of proceedings” model—under which the prosecutor could act only upon the formal handover of cases by Ukraine—attracted only modest support, and it was regularly connected with the question of immunities. The argument here was that Ukraine had asked for the creation of an international tribunal as it was unable to lift immunities within its own domestic system. Under a model of transfer of proceedings, that problem would remain unaddressed and the purpose of the project as such would be undermined. Nevertheless, the approach was largely set aside only at the Bucharest convening of the Core Group in June 2024, after Ukraine expressed its clear preference for greater prosecutorial independence for the Special Tribunal. The eventual compromise, confirmed at the Brussels meeting in February 2025, authorizes Ukraine’s national Prosecutor-General to refer cases, evidence, and information to the Special Tribunal, while also allowing the tribunal’s prosecutor to initiate proceedings independently within the parameters set out in the Statute. This hybrid approach aims to preserve a level of independence for the tribunal while enhancing Ukrainian ownership.
It is also worth emphasizing that the final text of the Special Tribunal’s Statute—particularly Articles 23 and 24—leaves some ambiguity over the precise procedural threshold for initiating investigations. It is not fully clear whether the prosecutor’s independent action requires, in practice, a formal referral from Ukraine, or whether such referrals are only one of multiple possible triggers for jurisdiction. This interpretive gap could become significant in politically sensitive situations, where the prosecutor’s willingness to act might be tested against Ukraine’s own prosecutorial or diplomatic priorities. In effect, while the compromise grants a dual pathway for triggering investigations, the exact interplay between Ukrainian referrals and proprio motu prosecutorial action will likely depend on the Statute’s eventual application and the political context in which it operates.
In short, Articles 23 and 24 of the Statute leave ambiguous whether the prosecutor may act proprio motu or only upon formal referral by Ukraine. This ambiguity may prove consequential. A broad reading could allow the prosecutor to open investigations independently, strengthening the tribunal’s autonomy but inviting accusations of politicization. A narrow interpretation would preserve Ukrainian sovereignty but risk transforming the STCA into a delegated domestic mechanism. How this provision is interpreted in practice will be central to the Special Tribunal’s future operations.
Legal Scope and Safeguards
The Special Tribunal’s mandate has been carefully crafted to complement existing international judicial mechanisms, particularly the ICC, and to avoid undermining them. Its jurisdiction is strictly limited to one crime—the crime of aggression. . The Statute also reflects an awareness of the need to preserve the integrity of the broader system of international criminal law.
In this context, it is important to note that the Core Group discussions included significant negotiations over language designed to safeguard the ICC and the body of international law jurisprudence from any restrictive interpretations of the Special Tribunal’s statute. In particular, Article 5 of the Statute contains a non-prejudice clause ensuring that nothing in the Statute shall be construed as limiting or derogating from existing international law. Article 46 also affirms that nothing in the Statute negates the existing obligations of ICC State Parties to cooperate fully with the Court in its investigations and prosecutions, including with respect to existing arrest warrants. The Special Tribunal, while international in participation, does not share the same legal status as the ICC. In particular, it does not meet all the standards required for an international tribunal. Its limitations on personal immunities, therefore, cannot be transposed to the ICC, which is a truly international tribunal established by a multilateral treaty that is currently ratified by 125 States. At the same time, it is hoped that the tribunal’s international character will grow as more States choose to support it, thereby expanding both its legitimacy and the range of considerations regarding its approach to questions of personal immunity.
Outcome, Analysis, and the Imperative of Universal Accountability for Aggression
Liechtenstein’s Position
We represented Liechtenstein in these discussions. From the outset, Liechtenstein played a pivotal role in galvanizing support for the Special Tribunal, consistent with Liechtenstein’s long-standing commitment to the international rule of law and with Liechtenstein’s leadership on accountability for the crime of aggression within the ICC framework. In our internal deliberations following Russia’s full-scale invasion of Ukraine in February 2022, we recognized early on the significant political hurdles to creating an aggression tribunal that met our criteria for legitimacy, independence, and legal strength. At the same time, we concluded that inaction in the face of what was arguably the most brazen act of aggression since the Second World War—and certainly since the adoption of the Kampala Amendments in 2010—would reinforce the perception that the crime of aggression remained normatively central, but practically unenforceable. For us, inaction was therefore not a viable option—it would have been neither in service of Ukraine nor in defense of public international law—which is why we initiated early discussions with like-minded partners in New York, particularly the Yale Club Roundtable in June 2022.
In parallel, we began advocating for the strengthening of the ICC’s jurisdiction over the crime of aggression, aiming to bring it in line with the Court’s jurisdiction over the other core crimes. Our dual commitment to ensuring accountability for the aggression against Ukraine and to upholding the integrity and development of international law shaped Liechtenstein’s contributions to the Core Group negotiations from start to finish.[34]
Liechtenstein’s negotiating positions within the Core Group were consistent and clear, and they were reflected in the discussion papers it presented at the Core Group meetings and the FAQ paper it co-drafted with key partners.[35] Liechtenstein consistently supported the establishment of a tribunal with sufficiently international character to overcome the personal immunities of the Troika, on grounds of both political principle and legal precedent. Accordingly, Liechtenstein advocated for a tribunal established by the UNGA for as long as that option remained viable. It also strongly supported the prosecutor’s proprio motu powers and opposed the inclusion of trials in absentia. Furthermore, Liechtenstein was among the most active proponents of incorporating the Rome Statute’s definition of aggression—one of the central issues in the negotiations.
Liechtenstein viewed its role in the Core Group as that of a principled supporter of Ukraine and a proponent for the protection and development of public international law. In instances where these priorities were in tension, we gave precedence to the latter. We actively participated in all Core Group convenings and consistently advocated for in-depth discussions of key issues. Over time, it became clear that the principal disagreements within the group were political rather than legal. As further negotiations were unlikely to produce deeper consensus, we joined those calling for a conclusion to the process and agreed to compromises that were difficult for us, while safeguarding our general positions on public international law.
Outcome
In sthe pring of 2025, following more than a dozen negotiation rounds, the draft Statute was finalized. Ukraine transmitted the relevant documents during the May meeting of the Committee of Ministers of the Council of Europe in Luxembourg. On June 24, 2025, the draft Statute of the Special Tribunal for the Crime of Aggression was adopted by the Committee of Ministers of the Council of Europe. Following the formal signing of the establishing agreement in Strasbourg on June 25, the Ukrainian Parliament ratified the treaty on July 15, 2025, thereby opening the way for ratification of the Enlarged Partial Agreement (EPA) by other Council of Europe member States.[36] Under the Council of Europe’s legal framework, an EPA allows a subset of its Member States—joined by non-members if they choose—to create a treaty-based mechanism within the organization’s institutional umbrella. This provides international legal personality while allowing flexible participation.
Throughout the negotiations, Liechtenstein faced a recurrent dilemma: how to advance accountability for Ukraine while safeguarding the integrity of public international law. In some instances—such as defending the Kampala definition of aggression—these interests aligned, although they were hard to achieve. In others, notably on trials in absentia and the Council of Europe venue, they diverged. Liechtenstein ultimately concluded that imperfection was preferable to paralysis.
The draft Statute adopted by the Council of Europe represents a political compromise. Substantive concessions were made, some of which were not easy to accept. They will have to be weighed against several positive outcomes. Chief among them are the creation of a sui generis accountability mechanism dedicated to the crime of aggression, public recognition of the aggression against Ukraine, and institutional anchoring within the Council of Europe, with which Liechtenstein enjoys a strong historical relationship. We are proud that our efforts contributed to the signed treaty between Ukraine and the Council of Europe, which will soon enable broader participation through the EPA, and that our substantive reservations with the Statute were made on the record when it was adopted.[37] The treaty adopts the Rome Statute’s definition of aggression, permits in absentia trials under procedural safeguards, and preserves a certain degree of prosecutorial discretion.
A significant limitation remains: the tribunal cannot lift personal immunities of sitting members of the Russian Troika—those most responsible for the aggression. Lifting these immunities had been a key benchmark Liechtenstein and many of its like-minded partners had set for themselves. However, the tribunal can still bring indictments against them and initiate proceedings once they leave office. It can also prosecute other senior officials not shielded by personal immunities, potentially including those from Belarus and the Democratic People’s Republic of Korea, whose leadership has been complicit in supporting the aggression against Ukraine.
While the tribunal lacks the ICC’s full capacity to override immunities, it remains a substantial innovation and does not set a negative precedent for the question of immunities under international law. It reflects a blend of legal creativity and political pragmatism.
Future Questions
The Core Group discussions were rigorous, prolonged, and at times contentious. Though often framed in legal terms, the core disagreements—especially regarding immunities—were ultimately political, as it was clear that overcoming personal immunities was legally possible if the Tribunal created was sufficiently international in nature. Although framed in legal terms, the disagreements over immunities reflected divergent political risk assessments about precedent-setting, reciprocity, and future exposure of senior officials. In this sense, law structured the debate, but politics determined its outer limits. Broader considerations, such as the tribunal’s potential role in a future peace process, were rarely discussed explicitly, though always present in the background. The evolving political dynamics surrounding Ukraine inevitably shaped negotiating positions and the sense of urgency within the group. Negotiations were also marked by an unusual division of coordination work. While Ukraine was formally in the lead and the convenor of the Core Group, the negotiating texts were regularly coordinated by the EU’s European External Action Service (EEAS), even though there was no common position among EU Member States on key issues such as immunities and transfer of proceedings. Once discussion started focusing on the Council of Europe option, the Legal Service of the Council of Europe played a key, though not exclusive role in leading the negotiations.
Liechtenstein continues to have reservations about limitations placed on the lifting of personal immunities for the Troika for this leadership crime. Likewise, we opposed the inclusion of in absentia trials due to long-standing due process concerns, although we understand their significance for Ukraine, particularly considering the immunities compromise.
On a positive note, the inclusion of the Rome Statute’s definition of aggression—reflecting customary international law—is a critical achievement. While we had initially favored a direct replication of Article 8 bis, we had no difficulty accepting the negotiated compromise, which retains the full definition while supplementing it with context-specific elements regarding the aggression against Ukraine. These additions were unnecessary in our view, but at the same time, not harmful either and acceptable as political accommodations.
The establishment of the Special Tribunal marks a significant moment in the evolution of public international law. It demonstrates that even in a fragmented multilateral system, there are innovative avenues to pursue accountability, particularly until the ICC’s Rome Statute is amended to bring its aggression jurisdiction in line with its other core crimes. And, the STCA’s exceptional character lies in the combination of factors present here: a manifest violation of the UN Charter, Security Council paralysis caused by the aggressor itself, a relevant legal determination by the UN General Assembly and the absence of any alternative forum capable of exercising jurisdiction for the time being.
This tribunal also contributes meaningfully to the ongoing debate about immunities in international criminal law. Domestic courts are unable to convict sitting heads of state for international crimes due to their immunity. By contrast, international tribunals such as the ICC have affirmed that neither personal nor functional immunities apply before them.[38] The Special Tribunal, created under a regional framework, introduces a novel hybrid: it can fully lift functional immunities and can even partially pierce personal immunities of sitting high officials, as the future prosecutor of the Special Tribunal may bring forward indictments for the crime of aggression.
This hybrid character raises a fundamental and unresolved legal question: at what point does a regional tribunal attain sufficient international character to fully override personal immunities? Should States outside the Council of Europe join the tribunal, and could that shift justify treating it as a fully international court with the authority to prosecute heads of state? At the time of writing, the ratification process is at a very early yet critical stage. The substantive discussions which were central to the Core Group’s negotiations are currently secondary to concerns about financing and the likelihood of ratification. The financing question in particular will likely be a litmus test for the viability of the Special Tribunal.
Conculsion
While the jury is still out, the Special Tribunal’s very establishment proves a crucial point: the frontiers of international criminal law are not fixed. Regional mechanisms can serve as laboratories of legal innovation, bridging the gap between national constraints, political hesitations of major powers, and global justice imperatives. And perhaps most importantly, the Special Tribunal demonstrates that the crime of aggression has a central place in the ongoing effort to promote international criminal justice. While some scholars may warn that regional tribunals may fragment international law, the STCA can also be seen as evidence that regional frameworks can serve as laboratories of legal innovation when global mechanisms stall. It complements rather than competes with the ICC, filling a normative vacuum ultimately created by the Security Council’s paralysis and inability to react to aggression committed by one of its permanent members. Politically, the STCA represents the outer boundary of what was achievable in a deeply divided negotiation even among those politically aligned: a mechanism that secures at least a measure of accountability while remaining sufficiently acceptable to a critical mass of supporting States. The effort to create the Special Tribunal has always been one important, but also small aspect of the Ukraine file and subject to the bigger political shifts and movements. At the time of writing, it is therefore unclear if States will muster the political will to see the effort through to the creation of an operational tribunal
Legitimacy in international justice derives not only from universality but from procedural integrity and victim consent. Although the STCA’s initial membership is regionally concentrated, its grounding in the Council of Europe—an organization defined by its commitment to the rule of law—and its leadership by Ukraine—the victim state—provide a dual source of legitimacy: institutional and moral. The challenge ahead is to broaden participation to non-European states.
Ultimately, the Special Tribunal is not merely about Ukraine. It has sparked a broader reconsideration of how the international community confronts aggression. It affirms that accountability is not optional, even when universal mechanisms like the ICC and UNGA are obstructed. It also provides a new model for regional leadership in defending the international legal order, echoing concerns about the erosion of norms against the use of force and the dangers of a world in which “might unmakes right.”[39]
In that sense, the Special Tribunal is more than a response to a single conflict. It embodies a principled recommitment to a cornerstone of the UN Charter: the prohibition of the unlawful use of force. We hope it will serve not only as a deterrent against future acts of aggression, but also as a meaningful step toward the long-overdue realization of universal accountability for this supreme crime before the ICC. This must remain our central objective—however difficult it may be to achieve. The current trends regarding the use of force in international relations are deeply troubling, making the criminalization of aggression—the gravest manifestation of unlawful force—more important than ever. The Special Tribunal for Ukraine is a sui generis mechanism of accountability, one whose ultimate place in the history of international law has yet to be determined. Its creation was an arduous and remarkable process—and one we should not have to repeat.
[1] Ambassador Christian Wenaweser is the Permanent Representative of Liechtenstein to the United Nations, a position he has held since 2002. Between 2008 and 2011 he also served as President of the Assembly of States Parties to the Rome Statute of the International Criminal Court (ICC). In that role, he presided over the first Review Conference of the ICC in 2010, which adopted amendments to the Rome Statute on the Crime of Aggression; Sina Alavi served as Liechtenstein’s Senior Legal and Political Adviser, representing the country in the Ukraine-led Core Group meetings on the establishment of a Special Tribunal for the Crime of Aggression against Ukraine, as well as in deliberations at the ICC Assembly of States Parties, the United Nations General Assembly Sixth Committee (Legal Affairs), and the International Court of Justice.
[2] For many years, Liechtenstein has consistently advocated, together with like-minded partners, for a stronger coalition of small and medium-sized States to act collectively as principled champions of an international order, based on the rule of law,s. concern that has recently been given more visibility in internatonal fora , including in Canada’s Prime Minister, Mark Carney widely cited remarks at the World Economic Forum in Davos in January 2026.
Mark Carney, Prime Minister of Can., Special Address at the World Economic Forum Annual Meeting (Davos) (Jan. 20, 2026), https://www.weforum.org/stories/2026/01/davos-2026-special-address-by-mark-carney-prime-minister-of-canada/.
[3] Int’l Crim. Ct., Review Conference Concludes with Adoption of Historic Amendments (June 11, 2010), https://www.icc-cpi.int/news/review-conference-concludes-adoption-histo… (announcing adoption of the Kampala Amendments on the crime of aggression).
[4] G.A. Res. 71/248, ¶ 1 (Dec. 21, 2016) (establishing the International, Impartial and Independent Mechanism for Syria); U.N. News, Russia, China Veto Security Council Referral of Syria to ICC (May 22, 2014), https://news.un.org/en/story/2014/05/468362.
[5] See Luke Harding, Ukraine Backs Plan for International Tribunal to Try Putin for Crime of Aggression, Guardian (Mar. 4, 2022), https://www.theguardian.com/world/2022/mar/04/ukraine-backs-plan-for-international-tribunal-to-try-putin-for-of-aggression.
[6] Philippe Sands, Putin’s Use of Military Force Is a Crime of Aggression, Financial Times (Feb. 28, 2022), https://www.ft.com/content/cbbdd146-4e36-42fb-95e1-50128506652c
[7]Statement of ICC Prosecutor, Karim A.A. Khan QC, on the Situation in Ukraine: Receipt of Referrals from 39 States Parties and the Opening of an Investigation (Mar. 2, 2022), Int’l Crim. Ct., https://www.icc-cpi.int/news/statement-icc-prosecutor-karim-aa-khan-qc-situation-ukraine-receipt-referrals-39-states
[8] Unlike genocide, war crimes or crimes against humanity, the crime of aggression is subject to a distinct jurisdictional regime under the Rome Statute.[8] Article 15 bis(5) excludes the Court’s jurisdiction over crimes of aggression committed by nationals of non-States Parties absent a Security Council referral, even where the victim State has accepted jurisdiction.
[9] Int’l Crim. Ct., ICC Judges Issue Arrest Warrants Against Vladimir Vladimirovich Putin and Maria Alekseyevna Lvova-Belova (Mar. 17, 2023), https://www.icc-cpi.int/news
[10] G.A. Res. 377 (V), Uniting for Peace (Nov. 3, 1950) (authorizing the General Assembly to act when the Security Council fails to exercise its primary responsibility).
[11] G.A. Res. ES-11/1 (Mar. 2, 2022); G.A. Res. ES-11/2 (Mar. 24, 2022); G.A. Res. ES-11/4 (Oct. 12, 2022).
[12]G.A. Res. A/RES/ES-11/L.6, Furtherance of Remedy and Reparation for Aggression Against Ukraine (adopted Nov. 14, 2022 by a recorded vote of 94 in favor, 14 against, and 73 abstentions); Roberto Rabel, Global South and Western Divergence on Russia’s War in Ukraine: Implications for World Order, Int’l Affs. 101 (3) 1005, 1005–21 (May 6, 2025), https://doi.org/10.1093/ia/iiaf008
[13] International Peace Institute, A Necessary Voice: Small States, Multilateralism, and the United Nations 3–7 (Apr. 2019), https://www.ipinst.org/wp-content/uploads/2019/04/1904_A-Necessary-Voice_Final.pdf (explaining that small States depend on international law and multilateral institutions, particularly the United Nations, to protect their sovereignty, security, and political independence).
[14] ANNEX draft elements for a resolution that was never circulated
[15] Statement of ICC Prosecutor, Karim A.A. Khan QC, to the ICC Assembly of States Parties 21st session at the First Plenary Meeting (Dec. 5, 2022), Int’l Crim. Ct., https://asp.icc-cpi.int/sites/asp/files/2022-12/ASP21-STMT-PROS-ENG.pdf
[16] Res. RC/Res.6, ¶¶ 4–6 (June 11, 2010) (mandating review of aggression provisions); Assembly of States Parties, ICC-ASP/S-1/Res.1 (July 9, 2025) (decision on ongoing harmonization efforts).
[17] U.S. Dep’t of State, U.S. Assistance to International Investigation of the Crime of Aggression Against Ukraine (Nov 14, 2023), https://2021-2025.state.gov/u-s-assistance-to-international-investigati…
[18] Council of Europe, Special Tribunal for the Crime of Aggression Against Ukraine: Frequently Asked Questions, https://www.coe.int/en/web/portal/special-tribunal-for-the-crime-of-aggression-against-ukraine-frequently-asked-questions (last visited Jan. 13, 2026) (stating that the Core Group comprised legal experts from approximately forty States, primarily from the Western and Eastern European regional groups—including the United States as part of the Western European and Other Group.
[19]Costa Rica, Guatemala and Japan were the only members of the Core Group from outside the Western and Eastern European regions.
[20] While international law jurisprudence indicates that international courts may set aside personal immunities, international law has not articulated a clear threshold for when a tribunal possesses sufficient international character to do so. The ICJ’s Arrest Warrant judgment affirmed the distinction between national and international courts without defining the latter category exhaustively. The Core Group negotiations unfolded against this legal indeterminacy.
[21] The Kosovo Specialist Chambers (KSC) is a temporary, hybrid court operating under Kosovo law but located in The Hague, Netherlands, and fully staffed by international judges and prosecutors. Its mandate is to investigate and adjudicate specific war crimes and crimes against humanity allegedly committed during and immediately after the Kosovo conflict (1998-2000).
[22] Matthew Mpoke Bigg & Oliver Slow, Ukraine Says It Is Investigating More Than 21,000 War Crimes and Crimes of Aggression Since Russia’s Invasion, BBC News (Jul. 14, 2022), https://www.bbc.com/news/world-europe-62073669
[23] UNGA Resolution A/RES/ES-11/5
[24] Claus Kreß, Keynote Address at the Council of Europe High-Level Conference on the Special Tribunal for the Crime of Aggression Against Ukraine (Mar. 2024), https://rm.coe.int/keynote-kress/1680af5a2d
[25] Charter of the International Military Tribunal art. 7, Aug. 8, 1945, 82 U.N.T.S. 279 (providing that “[t]he official position of defendants, whether as Heads of State or responsible officials in Government Departments, shall not be considered as freeing them from responsibility or mitigating punishment”);
Prosecutor v. Taylor, Case No. SCSL-2003-01-I, Decision on Immunity from Jurisdiction, ¶¶ 38–52 (May 31, 2004) (holding that a sitting head of state enjoys no personal immunity before an international criminal tribunal);
Arrest Warrant of 11 April 2000 (Dem. Rep. Congo v. Belg.), Judgment, 2002 I.C.J. 3, ¶ 61 (recognizing that personal immunities do not bar prosecution before “certain international criminal courts”);
Prosecutor v. Al Bashir, Case No. ICC-02/05-01/09-397-OA, Judgment on the Appeal, ¶¶ 113–19 (May 6, 2019) (holding that no head-of-state immunity applies before the ICC).
[26] President Volodymyr Zelenskyy, Speech to Representatives of the Public, Political, and Expert Circles of the Kingdom of the Netherlands and International Institutions Based in The Hague (May 3, 2023), https://www.president.gov.ua/en/news/vistup-volodimira-zelenskogo-pered-predstavnikami-gromadskos-82653 (urging establishment of an international tribunal to try Russian leaders for crimes of aggression and other core international crimes).
[27] (“#4 down”, i.e. all officials ranking below the troika was the diplomatic shorthand used by some in the negotiations).
[28] See, e.g., Claus Kreß, The Crime of Aggression as Customary International Law, 10 J. Int’l Crim. Just. 901, 915–22 (2012).
[29] Art. 24: For the purpose of this Statute, in the context of the aggression against Ukraine, an act of aggression which is determined by its character, gravity and scale to constitute a manifest violation of the Charter of the United Nations, shall also be deemed to constitute a war of aggression.
[30] Lukáš Mareček & Nathalie Awada, Legacy of the Special Tribunal for Lebanon: Terrorism as a Crime Under International Customary Law, Criminal Responsibility of Legal Persons and Trial in Absentia, The Lawyer Q. Vol. 15 No. 1 (Mar. 3, 2025), https://tlq.ilaw.cas.cz/index.php/tlq/article/view/631 (noting that the STL’s allowance for trials in absentia “diverges from prevailing trends” and is “unlikely to be adopted by other tribunals”).
[31] Article 28 of the STCA Statute https://search.coe.int/cm#{%22CoEIdentifier%22:[%220900001680b678ca%22],%22sort%22:[%22CoEValidationDate%20Descending%22]}
[32] Art. 28.4(3) In case of a conviction in the absence of the accused, the convicted person shall have the rightto a retrial in his or her presence before the Special Tribunal or a successor mechanism, unless he or she:
(a) has waived in writing his or her right to a retrial; or
(b) accepts the judgment.. this means that retrials are possible, even after long years have elapsed, and theat the Tribunal incurs significant additional costs in such a scenario.
[33] The concern that the tribunal could turn into a bargaining chip in possible peace negotiations was repeatedly rebutted by Ukraine in the negotiations, but never completely disappeared.
[34] ANNEX LI-drafted non-papers
[35] ANNEX LI-drafted discussion papers
[36] Council of Europe, President Zelenskyy and Council of Europe Secretary General Berset to Sign Agreement on Special Tribunal for Aggression Against Ukraine (Jun. 2025), https://www.coe.int/en/web/portal/-/president-zelenskyy-and-council-of-europe-secretary-general-berset-to-sign-agreement-on-special-tribunal-for-aggression-against-ukraine
[37]Agreement Between Ukraine and the Council of Europe on the Establishment of a Special Tribunal for the Crime of Aggression Against Ukraine, (Jun. 2025), https://search.coe.int/cm#{%22CoEIdentifier%22:[%220900001680b678c9%22],%22sort%22:[%22CoEValidationDate%20Descending%22]}
[38]Arrest Warrant of 11 April 2000 (Dem. Rep. Congo v. Belg.), Judgment, 2002 I.C.J. 3;
Prosecutor v. Taylor, Case No. SCSL-2003-01-I, Decision on Immunity from Jurisdiction (May 31, 2004); Prosecutor v. Al Bashir, Case No. ICC-02/05-01/09, Judgment on the Appeal (May 6, 2019).
[39]Oona A. Hathaway & Scott J. Shapiro, Might Makes Right? The United Nations and the Use of Force, Foreign Affairs (July/Aug. 2025).