It emerges from the judgment of the Court of Justice of 5 October 2000, in Case C-376/98, Germany v Parliament and Council, that to construe Article 100a(1) of the EC Treaty (now Article 95) as meaning that it vests in the Community legislature a general power to regulate the internal market would not only be contrary to its express wording but would also be incompatible with the principle embodied in Article 3b of the EC Treaty (now Article 5) that the powers of the Community are limited to those specifically conferred on it.

In order to determine whether a dual legal basis is necessary for Community action, the Court of Justice verifies, in Case C-42/97, Parliament v Council, whether culture is an essential component of the contested decision, in the same way as industry, and cannot be dissociated from industry or whether the ‘centre of gravity’ of the decision is to be found in the industrial aspect of the Community action.

It emerges from the judgment of the Court of Justice of 17 March 1993, in Case C-155/91, Commission v Council, that the fact that some provisions of a directive affect the functioning of the internal market is not sufficient for Article 100a of the EC Treaty (now Article 95) to be selected as a legal basis. Recourse to that provision is not justified where the measure to be adopted has only the incidental effect of harmonising market conditions within the Community.

It emerges from the judgment of the Court of Justice of 13 September 2005, in Case C-176/03, Commission v Council, that, because of both their aim and their substance, Articles 1 to 7 of Council Framework Decision 2003/80/JHA on the protection of the environment through criminal law have as their main purpose the protection of the environment and could have been properly adopted on the basis of Article 175 of the EC Treaty. In those circumstances, the entire Framework Decision, based on Title VI of the EU Treaty, encroaches on the powers which Article 175 of the EC Treaty confers on the Community and, being indivisible, infringes Article 47 of the EU Treaty under which none of the provisions in the EC Treaty may be affected by a provision of the EU Treaty.

It emerges from the judgment of the Court of Justice of 11 June 1991, in Case C-300/89, Commission/Council, with regard to an action for annulment of the Directive on waste from the titanium dioxide industry, that, in the present case, even if the Council’s power is based on two provisions of the Treaty, recourse to the dual legal basis is excluded since one of the enabling provisions at issue requires recourse to the cooperation procedure whereas the other requires the Council to act unanimously after merely consulting the European Parliament.

According to the Court of Justice, in its judgment of 13 November 1990, in Case C-331/88, Fedesa and Others, by virtue of the principle of proportionality, the lawfulness of the prohibition of an economic activity is subject to the condition that the prohibitory measures are appropriate and necessary in order to achieve the objectives legitimately pursued by the legislation in question, it being understood that, where there is a choice between several appropriate measures, recourse must be had to the least onerous, and the disadvantages caused must not be disproportionate to the aims pursued.

It emerges from the judgment of the Court of 29 November 1959, in Case 8-55, Fédération charbonnière de Belgique/High Authority, that the High Authority enjoys a certain independence in determining the implementing measures necessary for the attainment of the objectives referred to in the ECSC Treaty or in the Convention on the transitional provisions which forms an integral part thereof.

The AETR judgment shows that powers which, at the outset, have not been conferred exclusively upon the European Community may become so progressively through the exercise of those powers by the Community. In this case, the implementation of a common transport policy by the Community, through the laying down of common rules of an internal nature (adoption of a regulation), excludes the possibility of concurrent powers on the part of the Member States throughout the sphere of transport. The Court of Justice, while aware that the system of internal Community measures may not be separated from that of external relations, concludes that Member States may no longer enter into agreements with third countries in this field.

In its judgment of 5 November 2002, in Case C-469/98, Commission v Finland, the Court of Justice emphasises that, even if the Community's external competence in the field of air transport may arise by implication from provisions of the Treaty, this case does not disclose a situation in which the Community's internal competence could effectively be exercised only at the same time as its external competence and, therefore, the Community could not validly claim that there was an exclusive external competence to conclude an air transport agreement with the United States of America.

In its Opinion 1/94 of 15 November 1994, the Court of Justice further develops its ERTA doctrine by pointing out that the Community’s exclusive external competence does not automatically flow from its power to lay down rules at internal level and that only in so far as common rules have been established at internal level does the external competence of the Community become exclusive.

In its judgment of 30 July 1996, in Case C-84/95, in response to a reference for a preliminary ruling, the Court of Justice analyses the scope of a regulation by which the Council gave effect to the decision of the Community and its Member States, meeting within the framework of political cooperation (CFSP), to have recourse to a Community instrument in order to implement in the Community certain aspects of the sanctions taken against the Federal Republic of Yugoslavia by the United Nations Security Council.

It emerges from the judgment of the Court of Justice of 14 July 1976, in Joined Cases 3, 4 and 6/76, Cornelis Kramer and Others, that the Community’s authority to enter into international commitments arises not only from an express conferment by the Treaty but may equally flow implicitly from other provisions of the Treaty, from the Act of Accession and from measures adopted, within the framework of those provisions, by the Community institutions.

According to the Court of Justice, in its judgment of 13 February 1969, in Case 14/68, Walt Wilhelm and Others v Bundeskartellamt, so long as a regulation adopted pursuant to Article 87(2)(e) of the EEC Treaty (now Article 83 of the EC Treaty) in the field of competition law has not provided otherwise, national authorities may take action against an agreement in accordance with their national law, even where an examination of the agreement from the point of view of its compatibility with Community law is pending before the Commission, subject, however, to the condition that the application of national law may not prejudice the full and uniform application of Community law or the effects of measures taken or to be taken to implement it.

Protocol (No 2) on the application of the principles of subsidiarity and proportionality, annexed to the Treaty on European Union and the Treaty on the Functioning of the European Union by the Treaty of Lisbon of 13 December 2007.

In its judgment of 12 November 1996, in Case C-84/94, United Kingdom v Council, in response to an action for the annulment of the directive concerning certain aspects of the organisation of working time, the Court of Justice rejects the United Kingdom's argument of non-compliance with the principle of subsidiarity. That argument claims that the Community legislature has not established that the aims of the directive would be better served at Community level than at national level.

It emerges from the judgment of the Court of Justice, in Case C-233/94, Germany v Parliament and Council, that Parliament and the Council complied with the obligation to give reasons as required under Article 190 of the EC Treaty (now Article 253), since they set out why they considered that their action was in conformity with the principle of subsidiarity by stating that, because of its scale, their action could best be achieved at Community level and could not be adequately achieved by the Member States.

In its judgment of 9 October 2001, in Case C-377/98, Netherlands v Parliament and Council, in response to the application for annulment of the directive on the legal protection of biotechnological inventions, the Court of Justice rejects the second plea (breach of the principle of subsidiarity), since the objective pursued by the directive could not be achieved by action taken by the Member States alone and, given the scale and effects of the proposed action, could be better achieved at Community level.

In its judgment of 12 July 2001, in Case C-189/01, H. Jippes and Others, the Court of Justice emphasises that the principle of proportionality, which is one of the general principles of Community law, requires that measures adopted by Community institutions do not exceed the limits of what is appropriate and necessary in order to attain the legitimate objectives pursued by the legislation in question: when there is a choice between several appropriate measures, recourse must be had to the least onerous, and the disadvantages caused must not be disproportionate to the aims pursued.

It emerges from the judgment of the Court of Justice, of 12 July 2005, in Joined Cases C-154/04 and C-155/04, Alliance for Natural Health and Others, that the relevant provisions of the Directive on the approximation of the laws of the Member States relating to food supplements, which prohibit the marketing in the Community of food supplements containing vitamins and minerals not included on the positive lists, are not invalid by reason of an infringement of the principle of subsidiarity or of the principle of proportionality. The objective pursued by the provisions cannot be satisfactorily achieved by action taken by the Member States alone and requires action to be taken by the Community. What is more, they are measures appropriate for achieving the objective which they pursue and, given the obligation of the Community legislator to ensure a high level of protection of human health, they do not go beyond what is necessary to attain that objective.