A decision by the Home Office to refuse a Workers and/or Temporary Workers sponsor licence or to suspend, downgrade or revoke an existing sponsor licence does not attract a right of appeal. Since 6 April 2016, there has been a 'pre-licence error correction' procedure which has enabled sponsors to challenge the refusal of a sponsor licence application where there has been a 'simple caseworking error' or where supporting evidence sent with the initial application has not been considered. This Practice Note looks at how to challenge a negative sponsor licence decision by way of judicial review. It focuses on assessing the merits of a challenge, the investigation process, discussions and negotiations with the Home Office, and the letter before action.