This article examines
the impact of unconscious bias in arbitration and, in particular, in
arbitrators’ challenges. Through the analysis of recent case law – including
the Swiss Sun Yang Case (2020), the ICC Court Monologue Challenge (2023), the
English Expert Case (2024) and the French Obituary Case (2023) – it highlights
how unconscious bias can shape decision-making, procedural conduct and
perceptions of fairness in arbitration. Arbitrators often deny partiality, yet
their conduct – such as dismissiveness, unequal favour, or culturally charged
remarks – can create reasonable doubts about lack of impartiality and
independence, regardless of intent or awareness. While not all instances of
unconscious bias warrant disqualification as an arbitrator, this article argues
that unconscious bias can be properly addressed through current standards for
independence and impartiality in key instruments such as the IBA Guidelines on
conflict of interests in international arbitration. Finally, it advocates for
bias-mitigation training and diversity to preserve arbitration’s legitimacy.