As mentioned earlier, the Commission has limited legislative power compared with the implementing power that in most national systems is delegated by the legislative branch to the executive. The purpose is to give effect to the legislation adopted by the Council and the EP and to implement it at European level. Originally, this power was exercised by committees consisting of representatives of the Member States and chaired by a Commission official, thereby the term comitology.^ These committees were tasked to scrutinise the Commission’s proposals and adopt formal opinions before the Commission proceeded. This procedure had been in ad hoc use since the early 1960s, and it was first through Decision 1999/468/EC  that principles and rules for comitology were established. The increasing recourse to framework legislation, the need for supporting legislation to agree on technical details, and long-standing disagreements on the role of various institutions and Member States in comitology procedures led to substantial amendment of Decision 1999/ 468/EC in 2006.  By then almost all areas of EU activity had some comitology. The number of comitology committees was then over 260 and they had adopted 1,800 measures.65
The comitology system was abolished through the Treaty of Lisbon on 1 December 2009, and was replaced by Articles 290 and 291 TFEU. These articles introduced two categories of act, namely delegated and implementing. In this way, a distinction was made between the Commission’s legislative and non-legislative acts. According to Article 290, the Council and the EP can through a legislative act empower the Commission to adopt delegated (non-legislative) acts to supplement or amend certain non-essential elements of a legislative act. The legislative act that delegates non-legislative power to the Commission must define the objectives, content, scope, and duration of the delegated power, and lay down the conditions to which the delegation is subject. These conditions may be that the delegation can be revoked by the EP and the Council or that the delegated act may enter into force only if it is not opposed by the EP or the Council within a prescribed period. Note that the Commission’s delegated acts are those that could have been adopted by the legislator itself.
When the EU legislator deems that uniform conditions for implementing EU legislative acts are necessary, such acts confer, according to Article 291 TFEU, implementing powers on the Commission. Unlike the case of delegated acts, the Council and the EP lack a controlling role with respect to the Commission’s exercise of implementing power. Such control is exercised by the Member States. A mechanism for this control was established by Regulation (EU) No 182/2011 (the Comitology Regulation). This regulation provides for two procedures: advisory and examination. The advisory procedure (Arts 2 (3) and 4 of the Comitology Regulation) is for implementing measures of a less sensitive nature, such as grant approvals. The procedure starts with the Commission’s draft of an act, which the advisory committee (consisting of a representative of each Member State chaired by a Commission official) considers and adopts an opinion on simple majority vote. The Commission takes account of the opinion, but is not legally bound by it.
The examination procedure (Arts 2(2), 5, 6, and 7 of the Comitology Regulation) is more significant with respect to environmental acts. The procedure is used for, inter alia, implementing measures of general scope, measures related to agricultural policy, environmental policy, and programmes with substantial budgetary implications. Under the examination procedure, the Commission can adopt a draft implementing measure if it has the support of a qualified majority of the examination committee. In the case of a negative committee opinion, the Commission may submit its draft to an appeal committee or prepare an amended version of its draft.
If the examination committee delivers no opinion, the Commission may adopt the implementing measure except in certain defined cases. In these cases, the Commission may choose to submit an amended draft.
The purpose of the rather complicated examination procedure is to ensure that the Commission’s implementation power is under the effective control of the Member States. As regards the environment, framework legal acts have increased in number in recent years. These acts normally contain specific provisions delegating to the Commission the power to adopt supplementary measures through the committee procedures for proper implementation of the acts. An example is Directive
2008/50/EC on ambient air quality.  Articles 28(2) and 29(2) of this directive empower the Commission to adopt implementing measures according to the comitology system. The Commission has adopted two implementing acts to fulfil its obligation in this respect.6®
H T Anker, K de Graaf, R Purdy, and L Squintani, ‘Coping with EU Environmental Legislation—Transposition Principles and Practices’ (2015) 27 Journal of Environmental Law 17—44
C Barnard and S Peers (eds) European Union Law (Oxford University Press, 2014)
P Craig and de Burca (eds) The Evolution ofEU Law (2nd edn, Oxford University Press, 2011) U Drobnig Principles of European Law (Oxford University Press, 2015)
-  Generally on comitology, see A Heritier, C Moury, C S Bischoff, and C F Bergstrom ChangingRules of Delegation, A Contest for Power in Comitology (Oxford University Press, 2013); J Blom-HansenThe EU Comitology System in Theory and Practice: Keeping an Eye on the Commission? (Palgrave, 2011);and C F Bergstrom Comitology, Delegation of Powers in the European Union and the Committee System(Oxford University Press, 2005).
-  Council Decision 1999/468/EC laying down the procedures for the exercise of implementingpowers conferred on the Commission  OJ L184/23. The background of this decision was anamendment in Art 145 of the EC Treaty (later Art 202) that was introduced by Art 10 of the SingleEuropean Act to address the problem of unequal footing of the various parties to the comitologysystem.
-  64 Decision 2006/512/EC amending Decision 1999/468/EC laying down the procedures for theexercise of implementing powers conferred on the Commission  OJ L 200/11.
-  A Hardacre and M Kaeding Delegated & Implementing Acts: The New Comitology (5 th edn,European Institute of Public Administration, 2013) 8.
-  Regulation (EU) No 182/2011 of the European Parliament and of the Council of 16 February2011 laying down the rules and general principles concerning mechanisms for control by MemberStates of the Commission’s exercise of implementing powers  OJ L55/13.
-  Directive 2008/50/EC of the European Parliament and the Council on ambient air quality andcleaner air for Europe  OJ L152/1.
-  See, eg, Commission Directive (EU) 2015/1480 amending several annexes to Directives 2004/107/EC and 2008/50/EC of the European Parliament and of the Council laying down the rules concerning reference methods, data validation and location of sampling points for the assessment of ambient air quality  OJ L 226/4.