As machine learning (ML) systems increasingly impact critical sectors such as hiring, financial risk assessments, and criminal justice, the imperative to ensure fairness has intensified due to potential negative implications. While much ML fairness research has focused on enhancing training data and processes, addressing the outputs of already deployed systems has received less attention. This paper introduces 'BiasGuard', a novel approach designed to act as a fairness guardrail in production ML systems. BiasGuard leverages Test-Time Augmentation (TTA) powered by Conditional Generative Adversarial Network (CTGAN), a cutting-edge generative AI model, to synthesize data samples conditioned on inverted protected attribute values, thereby promoting equitable outcomes across diverse groups. This method aims to provide equal opportunities for both privileged and unprivileged groups while significantly enhancing the fairness metrics of deployed systems without the need for retraining. Our comprehensive experimental analysis across diverse datasets reveals that BiasGuard enhances fairness by 31% while only reducing accuracy by 0.09% compared to non-mitigated benchmarks. Additionally, BiasGuard outperforms existing post-processing methods in improving fairness, positioning it as an effective tool to safeguard against biases when retraining the model is impractical.

Lior Rokach is a computer scientist. He is a professor and the former chair of the Department of Software and Information Systems Engineering (SISE) at Ben-Gurion University of the Negev (BGU). Lior was born in 1972 in Holon, Israel. He completed his B.Sc., M.Sc., and Ph.D. in 1998,1999, and 2004 respectively at Tel-Aviv University. His research interests lie in designing and analyzing Machine Learning and Data Mining algorithms and their applications in Recommender Systems, Cyber Security, and Medical Informatics.