Article 34 TFEU/28EC/30EEC

4 The development of case-law on Article 28 EC.
The ECJ has been far from being consistent in its case law on Article 28 EC. In Dassonville and Cassis it provided a very wide formula in its judgments of what should be regarded as measures having effects equal to quantative restrictions under Article 28. That on the other hand led to problems in setting limits to the outer boundaries of the Article, which later led to the ECJ ́s decision in Keck and Mithouard, which was intended to limit the scope of the Article.
4.1 The basic rules.
According to Article 28 EC ”quantative restrictions on imports and all measures having equivalent effect shall be prohibited between Member States”.
The first question which arises when one reads Article 28 is what can be considered to be ”quantative restictions”. That came into consideration in the Geddo case in 1973, and was defined very broadly there.9
When it had been defined what ”quantative restrictions” were, according to Article 28, the next question which arose was of course what could be regarded to be ”measures having equivalent effect” to quantative restrictions. The Commission provided guidance to the Member States to the meaning and scope of the term by passing Directive 70/50, and in Article 2(3) of the Directive the Commission provided a non-exhaustive list of measures capable of having effect equivalent to quantative restrictions. The Directive is not applicable anymore but still it continues to give a general idea of the scope of the term “measures having equivalent effect” in Article 28.10