Gambling is deemed to be an economical activity pursuant to article 57 TFEU (article 50 TEU), and therefore falls within the scope of the Treaty (this principle was first established in the Schindler case, which is a milestone in this respect).
Two essential liberties apply to cross border gaming: freedom of establishment under article 49 TFEU (article 43 TEU), and freedom to provide services under article 56 TFEU (article 49 TEU). Both articles 49 and article 56 TFEU prohibit discriminatory measures that limit such liberties. Such restrictions can be justified only on the grounds of article 52 TFEU (article 46 TUE) in other words, for public reasons, public security and public health.
This means that, according to the Treaty principles, on the one hand, gaming is deemed an economical activity which must be permitted to move without any restrictions within the European market and, on the other hand, in consideration of the potential risks which it entails for customers, national authorities must intervene in order to limit such dangers.
Regardless of the fact that Member State regulations are inspired by the same general common directive criteria, the application of the subsidiary principle, which enables Member States to achieve such general protection principles due to discretionary margins, the resulting scenario at European level remains extremely varied, characterised by huge differences among the Member States: i.e. with regard to the choice of regime to access to the market (by an authorization or concession) the adoption of a numerus clausus system versus an open system for the grant of the licenses, and particularly in respect of the restrictions criteria to access the gaming market.
European decisions have clarified that market restrictions are accepted only when they are:
3.Aplied on the grounds of the proportionaly principle.
1.a Member State cannot exercise promotional activities and encourage consumers to gamble on the one hand and justify market restrictions on the grounds of public order on the other. An increasing gaming offer provided by the public sector is therefore a contradiction to restrictive gaming policies;
2.the procedure to obtain licenses must be transparent and non discriminatory;
3.a Member State is free to adopt the protection system that it deems proper to provide safeguard of the interests that justify access restrictions; in any case, the restrictive measures cannot exceed the defined objectives, particularly when the operator is subject to controls in its home country.
However, regardless of the discretionary margin provided by the application of the subsidiary principle, the deeds and behaviour of National authorities must comply with the primary freedoms of the Treaty. The exercise of discretionary power must be limited, which means it must be exercised on the grounds of objective criteria and used in a non arbitral manner.
 The differences among member states has been described by the studies conducted by the Swiss Institute of Comparative law. See http://ec.europa.eu/internal_market/services/gambling_en.htm
 A constant point of reference for the determination of the restrictive criteria is the notorious Gambelli case, C-243-01.