1.

The second subparagraph of Article 19(1) TEU, read in conjunction with Article 47 of the Charter of Fundamental Rights of the European Union,

must be interpreted as meaning that it does not preclude measures taken by the president of a national court which consist in designating judges assigned to one chamber of that court to sit temporarily in another chamber of that court, while continuing to sit in their chamber of origin, even though those judges have not consented to that appointment, they have no judicial remedy to challenge it, that appointment entails an increase in the workload of the judges concerned and requires their involvement in matters outside their area of specialisation, and that president has been appointed to the same court under conditions which are incompatible with the requirements arising from the second subparagraph of Article 19(1) TEU, provided that such measures are based on legitimate reasons relating in particular to the proper administration of justice, they are taken on the basis of the national rules governing the court in question, they are temporary and strictly limited in time, they do not call into question the assignment of the judges concerned to their chamber of origin and they do not result in any demotion or removal of those judges from the cases for which they are responsible.

2.

Article 3(3)(b) of Directive 2004/17/EC of the European Parliament and of the Council of 31 March 2004 coordinating the procurement procedures of entities operating in the water, energy, transport and postal services sectors, as amended by Commission Regulation (EC) No 1177/2009 of 30 November 2009, read in conjunction with Article 20(1) of Directive 2004/17, as amended,

must be interpreted as meaning that the purchase, by a public electricity trading undertaking, of green certificates, within the meaning of points (k) and (l) of the second paragraph of Article 2 of Directive 2009/28/EC of the European Parliament and of the Council of 23 April 2009, on the promotion of the use of energy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC, constitutes an activity pursued for the purpose of supplying electricity to fixed networks intended to provide a service to the public in the field of electricity production, transport or distribution.

3.

Article 1(4) of Directive 2004/17, as amended by Regulation No 1177/2009, read in conjunction with Article 14 and Article 17(2) of Directive 2004/17, as amended,

must be interpreted as meaning that:

4.

Article 2d(1)(a) of Council Directive 92/13/EEC of 25 February 1992 coordinating the laws, regulations and administrative provisions relating to the application of Community rules on the procurement procedures of entities operating in the water, energy, transport and telecommunications sectors, as amended by Directive 2007/66/EC of the European Parliament and of the Council of 11 December 2007,

must be interpreted as meaning that the conclusion of a contract in disregard of the rules on the award of public contracts is subject to the penalty provided for in that provision.

5.

The principle of the prohibition of abuse of rights must be interpreted as meaning that it does not preclude a contracting entity from seeking the annulment of a contract which it has concluded with a supplier on the ground that that contract was concluded in breach of the rules on the award of public contracts, even though the real reason for that claim is a reduction in the profitability of the performance of that contract.