Semi-Automated Offside Technology in Professional Football: A Critical Case Study on the Necessity of Explainable and Deterministic Artificial Intelligence in High-Stakes Decision Systems

Background: Semi-automated offside technology (SAOT) deployed across European professional football leagues represents a critical case study illustrating the urgent necessity for explainable artificial intelligence (XAI) and deterministic algorithmic systems in high-stakes decision-making contexts.Methods: This study employs a mixed-methods approach combining technical system analysis of SAOT specifications, quantitative examination of publicly available VAR decision statistics from La Liga's 2024-25 season, content analysis of media-documented technical failures, and governance framework analysis against established algorithmic accountability principles.Results: Empirical evidence reveals that in La Liga's 2024-25 season, Barcelona gained approximately 7 points from net favorable VAR decisions while Real Madrid lost 7 points from adverse calls—the worst balance in the league. Documented technical failures include wrong defender selection in Celta Vigo matches, a power outage eliminating VAR oversight during a disputed penalty, and system misinterpretation of goalkeeper touches. Mathematical quantification of measurement uncertainties (34 cm total error from temporal, spatial, and calibration sources) reveals that precision claims exceed physical capabilities.Conclusions: The legitimacy crisis stems not from whether systematic bias exists but from the structural impossibility of detection under current opacity. When Spanish authorities leaked full VAR audio recordings, the federation responded not with transparency reforms but by dispatching police to investigate the leak—exemplifying governance structures that prioritize control over accountability. This research proposes mandatory open-source algorithms, real-time audit logs accessible to affected parties, independent calibration verification, and genuine appeal mechanisms with remedial authority.