Justice Recoded? Why It Matters that the International Criminal Court Embraced Open-Source Software and Ditched Microsoft

On 31 October 2025, the International Criminal Court (Court) confirmed reports that it is replacing its Microsoft Office Suite with openDesk– open-source software (OSS) developed by Germany’s ZenDiS (Center for Digital Sovereignty). That development is hardly surprising – and, for some, “about time”. Nevertheless, it bears important implications for the Court’s daily ability to fulfill its mandate, and symbolic value in exemplifying how technology has moved to the heart of geopolitics, where OSS is increasingly presented as a primary tool for realising so-called “digital sovereignty.”

Others have analysed US sanctions against the Court (here, here and here) and, specifically, their implications for its artificial intelligence (AI) and evidence submission platforms, especially considering Microsoft’s – a US headquartered multinational corporation – close partnership with the Court. Yet the Court’s (proprietary) software dependencies run far deeper and wider, encompassing every organ and almost every daily operation; and its novel shift towards OSS belongs within a larger geopolitical conversation.

This blog post asks: why does the Court’s embrace of OSS matter for (a) realising its mandate; (b) providing a practical roadmap for other international courts and tribunals (ICTs); and (c) engaging the broad trend of adopting OSS as a tool for advancing one’s digital resilience in States and the United Nations (UN) alike?

Background

Anxieties have grown over these past months within the Court and amongst its supporters, as the second Trump Administration has imposed multiple sanctions via Executive Order (February and August) against the Court and its personnel. Those sanctions respond to and pressure the Court over its 2024 arrest warrants for Israel’s Prime Minister, Benjamin Netanyahu and Yoav Gallant, his former Minister of Defense, for alleged war crimes and crimes against humanity in Palestine. 

As Thorne has observed, under those sanctions, US “persons” (which includes a “corporation, group, subgroup, or other organization”) cannot fall under sanctions themselves. Yet they cannot provide services to sanctioned foreign person(s) lest they face substantial civil and criminal penalties. Consequently, Microsoft and other US headquartered companies are probably wary of working with the Court. They may restrict or remove services, potentially even favouring overcompliance given the sanctions’ chilling effects, fear and uncertainty. Harbouring concerns, the Court reportedly backed up evidence in January. 

Subsequently, concerns have escalated sharply. In May, Microsoft allegedly “cancelled” the email address of Prosecutor Khan – which Microsoft denied unequivocally. In September 2025, Trump reportedly considered “entity-wide” sanctions against the Court – triggering “emergency internal meetings” on “impact[s] of potential blanket sanctions” and searches for “alternative suppliers for […] software.” Insofar as the Court depends on US companies, such sanctions could seriously jeopardise its basic operations, preventing software, banking and other vendors from servicing the institution. 

Software that advances the Court’s mandate 

The Trump-ICC-Microsoft saga illustrates how deep dependencies upon US (technology) companies can be weaponised in furtherance of political objectives, threatening the Court’s functionality. For the ICC, the US sanctions are a “flagrant attack” against “independence of an impartial judicial institution” whose mandate to prosecute international crimes comes from its 125 States Parties, as enshrined in the Rome Statute. The President “firmly reject[ed]” any attempt to “politicise our judicial function” and condemned how those sanctions “harm” independence and “deprive millions of innocent victims […] of justice.” 79 States Parties further collectively decried sanctions for potentially jeopardising confidentiality and safety.

Calls for OSS solutions were swift. Open-Source Business Alliance advocated for adoption of “alternatives” at “full speed” to advance “digital sovereignty,” while The Netherlands urged reduced reliance on US providers. 

The distinctive nature of OSS certainly lends itself towards strengthening and safeguarding the Court’s ability to pursue its mandate. Developed by a global community, OSS is publicly available source code with a license permitting anyone to use, modify, and distribute, amongst other criteria. 

This approach furthers transparency, interoperability, competiveness, equality and innovation, fostering accessible yet autonomous and secure software by avoiding vendor lock-in, and generally cost-effective solutions. It advances the Sustainable Development Goals (ECOSOC Resolution 2021/30), and UN values (2023 Report, p.11). Likely, OSS would satisfy general procurement principles in the Court’s Financial Regulations and Rules (Rule 110.12), requiring “due consideration” of: 

1. best value for money; 
2. fairness, integrity and transparency; 
3. effective international competition; and 
4. interests of the Court.

Importantly, OSS is not a “fringe” solution. Studies estimate that OSS constitutes between 70 to 90 percent of modern software components, with a value of USD $8.8 trillion worldwide. Thus, it is already a mainstream tool for international lawyers. Furthermore, select OSS projects explicitly advance international law, including international criminal law and human rights, such as through tools for secure communication (Signal) and mapping crimes/rights violations (Uwazi).

Although OSS strategically advances the Court’s mandate, it is not a panacea or a “perfect solution” (should that exist). Firstly, “open” does not necessarily mean that “accountable,” “ethical” or “human rights compliant.” Decisions on what digital tools, and what software we use (open or closed) have real world consequences, and may even enable violations of international law. For instance, NGOs have raised the alarm at Israeli military intelligence deploying Microsoft, and the “Post Office Horizon Scandal” – the UK’s “most widespread miscarriage of justice” – blamed innocent postmasters for inconsistencies arising from faulty (proprietary) software, with deadly consequences. 

Secondly, the OSS ecosystem is not a vacuum from geopolitical dynamics, encompassing US sanctions (e.g. GitHub – the world’s largest repository of OSS – is a Microsoft subsidiary, and has restricted developer accounts in North Korea and beyond). The Court has weighed up relative risks and benefits, and decided that OSS is the best solution for securing its digital future.

Roadmap for other ICTs

The Court’s noteworthy shift towards OSS may spark similar conversations about software dependencies amongst ICTs, particularly those with common vendors and strategic partners like the UN International Computing Centre (bearing the rather duplicative acronym “UNICC”) who may support transitions. 

While the ICC has closely partnered Microsoft (including “Project Harmony” for AI-based evidence management and cloud storage), they are not alone. Microsoft is common across ICTs, the UN system and public administrations.  In 2021, the UNICC announced that it was helping its partner organisation, the International Court of Justice (ICJ), with its “digital transformation [to] optimise and secure its mission,” including organisation-wide implementation of Microsoft 365 Teams. 

The UNICC likewise has partnered with the Court. It is the “largest strategic partner for common, trusted, and cybersecure digital foundations” across the UN ecosystem, facilitating “adoption of required technologies to better serve global needs” encompassing cybersecurity, cloud and data. That relationship presumably includes advising on which software solutions befit an ICT’s specialised operations and purposes, and – where necessary – how to transition. 

While expert guidance may inform its decision-making, the Court is an independent court responsible for its own procurement – over which its Registrar holds authority (Rule 110.13). As a UN organ, the ICJ uses those procurement practices – requiring potential vendors to register with UN Global Marketplace – although it retains responsibility for its own acquisitions. Neither process precludes uptake of OSS, but each necessitates tailored administrative procedures.

Growing trend rather than an anomaly

As the technology trade wars escalate and their consequences reverberate around markets, many States and the European Union (EU) have embraced OSS to bolster digital resilience to external political and economic pressures – often described as “digital sovereignty.” The latter is holding serious discussions about protecting its public administrations, which are deeply entwined with US tech, especially Microsoft – holding approximately 73-80% market share of public sector productivity software. 

The Court’s transition to OSS is veritably inseparable from broader geopolitical dynamics. Firstly, it is reflective of this growing trend. Across Europe, several governments reportedly have been transitioning their public administrations from Microsoft to OSS. That is subnational (e.g. Germany’s  Schleswig-Holstein; Spain’s Andalusia and Valencia, France’s Lyon); national (e.g. France, Denmark, and Austria’s Armed Forces); and regional (European Commission). OSS is also favoured in procurement. “Open by default” is the first UN Open Source Principle, whilst The Netherlands require “open, unless…” for its government-developed software.

Secondly, the Court’s experiences have pushed several policymakers down that path (here, here, here). Finally, the Court’s decision not only reflects this broader trend towards OSS, but also directly benefits from resultant European infrastructure for digital independence: openDesk is the flagship product of ZenDiS, a German federal government owned limited liability company that also supports the EU’s new Digital Commons EDIC, established in October 2025. 

Conclusion

The Court’s pragmatic shift to openDesk has reflected, driven and relied upon a larger geopolitical trend of States and the UN embracing OSS as a critical tool for realising their digital autonomy and resilience. That trend is unlikely to cease anytime soon. 

Currently, the Court has a long road lying ahead in disentangling its complicated web of software dependencies after its decades of largely relying upon US tech’s (proprietary) solutions – a challenging but broadly necessary step in seeking to minimise structural risks, and to increase digital resilience in these uncertain times.