General definition of the concept 

In accordance with Article 102 any abuse by one or more undertakings of a dominant position within the internal market or in a substantial part of it shall be prohibited as incompatible with the internal market in so far as it may affect trade between Member States.

This statement implies, that in order to apply Article 102 the undertaking’s abusive behavior should affect the trade between the countries in European Union.

The main idea is a jurisdictional limit that determines the difference between national law of Member States and EU law that may be applied in certain anticompetitive situations.More precisely, any abusive behavior that threatens somehow a trade between Member States, for example, leads to unfair conditions for trade on prices, quantities; limiting production, markets or technical development to the prejudice of consumers; applying dissimilar conditions to equivalent transactions with other trading parties, thereby placing them at a competitive disadvantage and so on, must be regulated by EU Law. If the trade between Member States is not affected, an undertaking’s behavior will be regulated, particularly, by national competition law. However, even in these cases there is an obligation on the competition authorities and courts of the Member States to apply Article 102 of the Treaty, where they apply national competition law to the cases which may affect trade between Member States. This obligation is reflected also in the Article 3(1) of the Regulation No 1/2003, when the competition authorities and courts of the Member States apply national competition law to any abuse prohibited by Article 102 of the Treaty, they must also apply Article 102 of the Treaty.

The main elements of the concept.

In accordance with Article 18 of the Guidelines, there are 3 main elements of the effect on trade:

1. The concept of “trade” includes not only selling or purchasing of goods and services across borders, but also it can be interpreted wider and involve all cross-border economic activity including establishment. Therefore, the trade between Member States is based on the principle a free movement of goods, services, persons and capital. Moreover, the trade activities must be "between Member States". This statement implies that only cross-border economic activity that involves at least two Member States should be affected. Moreover, the abuse must affect not the whole two Member States, but even a part of a Member State, when the effect on trade is appreciable.
2. In accordance with the case law of the Court of Justice, the notion "may affect" implies that it must be possible to foresee with a sufficient degree of probability on the basis of a set of objective factors of law or fact that the agreement or practice may have an influence, direct or indirect, actual or potential, on the pattern of trade between Member States.

3. The assessment of “appreciability” is a measurable element and depends on the conditions and specifics of every certain situations, in particular the essence of the each agreement, practice and decision, and abusive behavior,  and the undertakings conditionsand the different circumstances on the market.