Court of Justice 5 December 2018, C-473/17 and C-546/17 (Repsol Butano SA and DISA Gas SAU v Administración del Estado.)

OPINION OF ADVOCATE GENERAL TANCHEV delivered on 5 December 2018 ( 1 ) Joined Cases C‑473/17 and C‑546/17 Repsol Butano SA (C‑473/17) DISA Gas SAU (C‑546/17) v Administración del Estado joined parties: Redexis Gas SL, Repsol Butano SA (Request for a preliminary ruling from the Tribunal Supremo (Supreme Court, Spain)) (Reference for a preliminary ruling — Energy — Internal market in natural gas —