Judgment of the Court (Sixth Chamber) of 14 May 2020.#Spenner GmbH & Co. KG v Bundesrepublik Deutschland.#Request for a preliminary ruling from the Bundesverwaltungsgericht.#Reference for a preliminary ruling – Environment – Scheme for greenhouse gas emission allowance trading in the European Union – Directive 2003/87/EC – Article 10a – Transitional regime for free allocation of allowances – Decision 2011/278/EU – Article 9 – Determination of the historical activity level – Significant change in the capacity of an installation which took place before the baseline period – Determination of the relevant baseline period.#Case C-189/19.