CERN terminated Russia/Belarus cooperation Nov 2024; ~500 scientists expelled

In November 2024, CERN terminated its cooperation with Russian and Belarusian institutions under European Union and Swiss sanctions following the 2022 invasion of Ukraine. Approximately 500 scientists affiliated with Russian institutions were expelled from LHC experiments, alongside a smaller cohort affiliated with Belarusian institutions whose contracts had ended earlier in 2024 (S-0041).

The action ended decades of direct Russian-state participation in the world's largest particle physics collaboration.

The case sits at the intersection of state action (sanctions regime), institutional decision (CERN's response to the regime), and access restriction. Researchers' continued participation in active experiments was determined by the geopolitical context of their institutional affiliation. Data those researchers had contributed to or relied on remained in CERN's hands; their ongoing research access was withdrawn.

This is a less-pure form of C-0020 (the data is still preserved on CERN's Tier 2 infrastructure), but it illustrates a closely related architectural property: research collaboration that depends on continued mutual access between institutions across jurisdictional boundaries is exposed to the jurisdictional regime's evolution. The Tier 3 architectural response — collaborator-side mirrors of relevant data, content-addressed snapshots, federated alternative compute paths — is independent of any host institution's bilateral relationship with any partner government.