National bias in international sports judging: a scoping review

The subjective nature of performance evaluation in aesthetic sports competitions makes it vulnerable to bias. Among these, national bias—where judges’ scores are influenced by their own and the athlete’s nationality—poses a significant threat to the integrity of competition outcomes. Existing literature is fragmented across sports, types of bias, theoretical explanations, and methodological approaches, and lacks an overarching synthesis. To address this gap, the present scoping review—conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2000 guidelines—synthesizes existing literature across four dimensions: (1) forms of national bias, (2) underlying mechanisms, (3) degree of intentionality, and (4) proposed mitigation strategies. Contributions addressing at least one of these dimensions were included regardless of type or quality.The review identifies national bias as a multifaceted phenomenon that manifests in several forms, including favoritism toward compatriots, penalization of their competitors, vote trading among judges, and reactive scoring based on perceived or expected national bias from colleagues. Vote trading reflects intentional manipulation, whereas other forms may arise unintentionally through cognitive or social mechanisms, complicating their detection and regulation. Existing countermeasures demonstrate limited effectiveness and often entail trade-offs, underscoring the need for more context-sensitive and robust interventions.