This paper examines the Spanish Competition Authority’s (CNMC) most ground-breaking implementation of the bidder exclusion for competition infringement since March 2019. Through an analysis of key case-law and regulations, we explore the CNMC’s traditional approach to debarment decisions and its subsequent reconsideration following influential judgments from the High Court of Justice of Catalonia. This study sheds light on the evolving landscape of the bidder exclusion, and provides valuable insights into its legal nature, application procedure, and potential effects on fostering fair and transparent competition in Spain.