The Directive takes as the benchmark for assessing the impact of a commercial practice the notion of the average consumer, a concept developed by the Court of Justice.
The Court of Justice, when weighing the risk of misleading consumers against the requirements of the free movement of goods, has held that, "...in order to determine whether a particular description, trade mark or promotional description or statement is misleading, it is necessary to take into account the presumed expectations of an average consumer who is reasonably well informed and reasonably observant and circumspect."
The average consumer, in the case law of the Court of Justice is a critical person, conscious and circumspect in his or her market behaviour. He or she should inform themselves about the quality and price of products and make efficient choices. For example, the "reasonably circumspect consumer" will not believe that the size of a promotional marking on a package corresponds to the promotional increase in the size of that product. The average consumer will not attribute to goods bearing the marking "dermatologically tested" any healing effects which such goods do not possess. However, the average consumer under the Directive is not somebody who needs little protection because he/she is always in a position to acquire available information and act wisely on it.
On the contrary, as underlined in Recital 18, the test is based on the principle of proportionality. The Directive adopted this notion to strike the right balance between the need to protect consumers and the promotion of free trade in an openly competitive market.
It is, first of all, based on the idea that, for instance, a national measure prohibiting claims (e.g. "puffery") that might deceive only a very credulous, naïve or cursory consumer would be disproportionate to the objectives pursued and create an unjustified barrier to trade.
Secondly, it is a concept which should be interpreted in line with Art 114 TFEU which provides for a high level of consumer protection. To achieve this, national authorities and courts should take into account various specific factors to complement the average consumer test.
The concept, which was not applied by certain Member States' courts, was also codified by the Directive to give national authorities and courts common criteria, to enhance legal certainty and to reduce the possibility of divergent assessments of similar practices across the EU.
Factors influencing the level of knowledge of the average consumer
The Court of Justice and the General Court (formerly known as the Court of First Instance), in assessing the likelihood of confusion of certain trade marks, have given some indications as to the behaviour of the average consumer and the fact that his/her behaviour may be influenced by other factors. This can apply by analogy to the concept of the average consumer in the Directive.
According to the General Court, "[t]he average consumer normally perceives a mark as a whole and does not proceed to analyse its various details...In addition, account should be taken of the fact that the average consumer only rarely has the chance to make a direct comparison between the different marks but has to place his trust in the imperfect image of them that he has retained in his mind. It should also be borne in mind that the average consumer's level of attention is likely to vary according to the category of goods and services in question."
And, according to the Court of Justice, "among the factors to be taken into account in order to assess whether the labelling at issue in the main proceedings may be misleading, the length of time for which a name has been used is an objective factor which might affect the expectations of the reasonable [average] consumer".
An example of this approach at a national level can be found in a recent judgment of an Italian administrative tribunal which, in relation to a decision of the Italian enforcement authority (ACGM), confirmed that:
"the level of knowledge of the average consumer cannot be assessed in merely statistical terms...social, cultural and economic factors, including the economic context and market conditions in which the consumer operates must be taken into account...the relevance of the characteristics of the goods and/or services together with the specifics of the relevant market sector cannot be disregarded. "
The case concerned misleading and aggressive commercial practices in the promotion and supply of electricity in Italy, after the liberalisation of the market. The Italian administrative court found that in the electricity market, the transition from a monopoly to a liberalized market not only altered the relationship between offer and demand, but had also increased the knowledge gap between consumers and traders. The court considered that, in such a context, the average consumer (i.e. somebody who is, in principle, reasonably well informed on the market conditions) could not be expected to have or gain the necessary knowledge or information to fill such a gap.
Essentially, the court took into account the fact that, in the electricity retail market, the average consumer had not yet adapted to the new market situation and that the reasonable level of knowledge one could expect from the average consumer had to be fixed accordingly.
Social, linguistic and cultural factors
In certain cases, social, linguistic and cultural features that are peculiar to a Member State may justify a different interpretation of the message communicated in the commercial practice by the competent authority or court.
In case of misleading advertising in the field of cosmetics the Court of Justice held that: "In order to apply that test to the present case, several considerations must be borne in mind. In particular, it must be determined whether social, cultural or linguistic factors may justify the term 'lifting', used in connection with a firming cream, meaning something different to the German [average] consumer as opposed to consumers in other Member States, or whether the instructions for the use of the product are in themselves sufficient to make it quite clear that its effects are short-lived, thus neutralising any conclusion to the contrary that might be derived from the word 'lifting' "
Therefore, on the basis of the average consumer test and despite the Directive's full harmonisation character, requiring the foreign trader to provide an additional piece of information could be justified on the basis of social, cultural or linguistic factors. In other words, because of these factors, the consumers of the country of destination, unlike those in the country of origin, would be misled by the omission of such an item.
National courts are those competent to make an assessment of such cultural, linguistic and social factors which warrant a different assessment of the unfair character of a commercial practice. All relevant factors must be taken into account, such as the circumstances in which products are sold, the information given to consumers, the clarity of such information, the presentation and content of advertising material, and the risk of error in relation to the group of consumers concerned.
The fact that a commercial practice is ordinarily employed in other countries without causing consumer protection concerns can be an element in assessing whether such a practice is unfair or not.
An additional point which national authorities and court should consider when assessing actual cases is that the average consumer test does not follow a statistical approach. A national court should be able to determine whether a practice is liable to mislead the average consumer exercising its own judgment by taking into account the presumed expectations of an average consumer without, in principle, having to commission an expert's report or a consumer research poll.
Paragraph 29 of the Opinion of Advocate-General in the "Estée Lauder" case, contains a basic but very useful description of how the average consumer test should be structured:
"...the test to be applied to any case of restriction on the sale or marketing of a product on the ground of protecting the consumer from misleading labelling or other accompanying information is whether its presence on the market would, in some material respect, be likely to mislead the hypothetical consumer so defined...The test should enable the national court to assess the facts of each case against this standard on the basis of its own judgment of how such a consumer would be affected. The standard involved, being based on a cumulation of four factors, is clearly a high one. Having regard to all the relevant surrounding circumstances of the case, and especially the selling arrangements employed by the vendor, the national court must be satisfied that the average consumer, who is reasonably well informed and observant about the product in question and who exercises reasonable circumspection when using his critical faculties to assess the claims made by or in respect of it, would be confused. The approach is thus not statistical. Market surveys may, in certain cases, be of assistance, although it must be remembered that they are subject to the frailties inherent in the formulation of survey questionnaires and often subject to diverging interpretation as to their significance. Accordingly, they do not absolve the national court from the need to exercise its own faculty of judgment based on the standard of the average consumer as defined in Community law. In conclusion, the important point is that a single Community-law test is now available and it would, therefore, be inappropriate for a national court to base its final decision as to confusion on statistical evidence regarding the probable effect on 10% to 15% of potential consumers."
National courts should take into account the fact that, the Directive not only codifies this case law but also further refines it by adapting the average consumer test when the interests of specific groups of consumers are at stake (Art 5(2)(b) of the Directive). This means that when the practice is addressed at a specific group of consumers, be they children or rocket scientists, national authorities and courts must assess its impact from the perspective of the average member of the relevant group.
For example, in the case of an advertisement for a ring tone for teenagers, one will have to take into account the expectations and the likely reaction of the average teenager of the group targeted and disregard those of an exceptionally immature or mature teenager belonging to the same group.
 Case C-210/96 Gut Springenheide and Tusky  ECR I-4657, para 31.
 Case C-470/93 Verein gegen Unwesen in Handel und Gewerbe Koln e.V. v Mars GmbH  ECR I-01923, para 24.
 Case C-99/01 Criminal proceedings against Gottfried Linhart and Hans Biffl  ECR I-09375, para 35.
 "Puffery" is a subjective or exaggerated statement about the qualities of a particular product, which is not meant to be taken literally, such as "best coffee in the world", or "it gives you wings".
 For vulnerable consumers see 2.3 below.
 See e.g. Joined Cases T-183/02 and T184/02 El Corte Inglés v Office for Harmonisation in the Internal Market (Trade Marks and Designs) ("Mundicolor")  ECR II-00965, para 68. See also case T-20/02 Interquell GmbH v Office for Harmonisation in the Internal Market (Trade Marks and Designs) ("Happydog")  ECR II-1001, para 37.
 Case C-446/07 Alberto Severi v Regione Emilia-Romagna, judgement of the Court of Justice of 10 September 2009, para 62.
 Tribunale Amministrativo Regionale del Lazio, Sezione I, Sentenza del 25 Marzo 2009 caso Enel S.p.A. contro Autorità Garante della Concorrenza e del Mercato .
 Case C-220/98 Estée Lauder Cosmetics GmbH & Co. OHG v Lancaster Group GmbH.  ECR I-00117, para 29.
 See Case C-313/94 F.lli Graffione SNC v Ditta Fransa  ECR I-06039, para 22: "the possibility of allowing a prohibition of marketing on account of the misleading nature of the trade mark is not, in principle, precluded by the fact that the same trade mark is not considered to be misleading in other Member States. As the Advocate General has observed in paragraph 10 of his Opinion, it is possible that because of linguistic, cultural and social differences between the Member States a trade mark which is not liable to mislead a consumer in one Member State may be liable to do so in another."
 Case C-313/94 F.lli Graffione SNC v Ditta Fransa  ECR I-06039, para 26.
 See Case C-315/92 Verband Sozialer Wettbewerb eV v Clinique Laboratories SNC et Estée Lauder Cosmetics GmbH.  ECR I-00317, para 21.
Case C-210/96 Gut Springenheide and Tusky v Oberkreisdirektor Steinfurt (hereinafter 'Gut Springenheide)  ECR I-4657, para 31, 32, 36 and 37. See also Case C-220/98, Estée Lauder Cosmetics GmbH & Co. ORG, v Lancaster Group GmbH, opinion of Advocate General Fennelly, para 28.