The principle of proportionality requires the Member States to adopt measures that are appropriate for attaining the objectives pursued and do not go beyond what is necessary for attaining them (see, to that effect, judgment of 17 April 2018, Egenberger, C‑414/16 , EU:C:2018:257 , paragraph 68 and the case-law cited). That principle, which is also guaranteed by Article 49(3) of the Charter of Fundamental Rights of the European Union (‘the Charter’), which provides that the severity of penalties must not be disproportionate to the criminal offence, is binding on Member States when they are implementing EU law, in accordance with Article 51(1) of the Charter. The severity of a penalty must thus correspond to the seriousness of the offence concerned, that requirement following both from Article 52(1) of the Charter and from the principle of proportionality of penalties in Article 49(3) of the Charter (see, to that effect, judgment of 20 March 2018, Garlsson Real Estate and Others, C‑537/16 , EU:C:2018:193 , paragraph 56 ). It follows that the principle of proportionality requires, first, that the penalty imposed corresponds to the seriousness of the offence and, second, that the individual circumstances of the particular case are taken into account in determining the penalty and fixing the amount of the fine.

The requirement of proportionality in Article 9a of Directive 1999/62/EC of the European Parliament and of the Council of 17 June 1999 on the charging of heavy goods vehicles for the use of certain infrastructures, as amended by Directive 2011/76/EU of the European Parliament and of the Council of 27 September 2011, cannot be regarded as having direct effect. The national court must, by virtue of its duty to take all appropriate measures, whether general or particular, to ensure the implementation of that provision, interpret national law in conformity with that provision or, if such an interpretation is not possible, disapply any national provision in so far as its application would, in the circumstances of the case, lead to a result contrary to EU law.

Consequently, for the principle of proportionality to be implemented in connection with Directive 1999/62, the Member States are required to adopt the legal measures needed in accordance with their national law, since Article 9a of the directive lays down an obligation which by its nature necessitates the intervention of a measure of those Member States, which have a wide margin of discretion when fulfilling that obligation. It should be observed in this connection that the directive does not contain more precise rules with regard to the establishment of those national penalties and, in particular, that it does not establish any express criterion for the assessment of the proportionality of such penalties (judgment of 22 March 2017, Euro-Team and Spirál-Gép, C‑497/15 and C‑498/15, EU:C:2017:229, paragraph 38). Therefore, as it necessitates the intervention of the Member States and leaves them a wide margin of discretion, Article 9a of Directive 1999/62 cannot be regarded, so far as its subject matter is concerned, as unconditional and sufficiently precise, which rules out its having direct effect.

A contrary interpretation would lead in practice to the removal of the discretionary power conferred on the national legislatures alone, for whom it is to design an appropriate system of penalties within the framework defined in Article 9a of Directive 1999/62. It follows that, in circumstances such as those of the main proceedings, the requirement of proportionality of penalties in Article 9a of Directive 1999/62 cannot be interpreted as requiring the national court to take the place of the national legislature.

(see paras 51-55, 62, operative part)