The foundations of a united Europe were laid on fundamental ideas and values to which the Member States also subscribe and which are translated into practical reality by the Community's operational institutions. These acknowledged fundamental values include the securing of a lasting peace, unity, equality, freedom, security and solidarity. The principle of solidarity of the European Union is a fundamental principle based on sharing both the advantages, i.e. prosperity, and the burdens equally and justly among members.
The principle of solidarity is often used in the context of social protection. For example, it was applied by the European Court of Justice in a case concerning complaints by self-employed workers that compulsory contributions to the mutual funds established to provide social protection violated the principles of free competition in the common market as laid down in Articles 81-82 EC (now Articles 101-102 TFEU). In Poucet v. Assurances générales de France (AGF) et Caisse mutuelle régionale du Languedoc-Roussillon (Camulrac), Pistre v. Caisse autonome nationale de compensation de l’assurance vieillesse des artisans (Cancava), Cases C-159/91 and C-160/91,  ECR 637, the French government in its arguments to the Court cited Article L 111-1 of the Social Security Code, which defines the principles of social protection in France: solidarity and compulsory affiliation.
The entire system of social security in France adheres to the solidarity principle – both within each regime and between them – in accordance with Article L 111-1. In its decision, the Court rejected the complaints by the self-employed workers. The Court characterised the French social security regimes as having a social objective in accordance with the principle of solidarity; their function is exclusively social and does not constitute economic activity necessary to constitute an enterprise within the meaning of Articles 81-82. The principle of ‘solidarity’, derived originally from the French system, brought into Community law by the Court of Justice, modified through adaptation to other Member State systems, and diffused through the European Community, may become one of those principles which characterise the European law on social protection.
Chapter IV (Articles 27-38) of the Charter of Fundamental Rights of the European Union is entitled ‘Solidarity.’ Articles 27 to 34 bear directly on employment and industrial relations: Workers’ right to information and consultation (Article 27), Right to collective bargaining and action (Article 28), Right of access to placement services (Article 29), Protection in the event of unjustified dismissal (Article 30), Fair and just working conditions (Article 31), Prohibition of child labour and protection of young people at work (Article 32), Family and professional life (Article 33), and Social security and social assistance (Article 34). The four remaining articles in the Solidarity Chapter are: Health care (Article 35), Access to services of general economic interest (Article 36), Environmental protection (Article 37) and Consumer protection (Article 38). They are solidarity rights in the social sense of the collective principle in the EC law on social protection.
Article 2 of the Treaty on European Union explicitly refers to the principle of solidarity, an affirmation crucial for the concept of Social Europe. The EU principle of solidarity has implications for the various rights concerned with employment, industrial relations and social protection in the EU Charter.
Implementation of the Solidarity Chapter of the EU Charter aims to build a bridge between programmatic solidarity rights (social and economic rights) and justiciable civil and political rights. Justiciable rights equate to effective and enforceable rights. The challenge is to establish clearly justiciable solidarity rights (e.g. trade union freedom of association, information and consultation, collective bargaining and collective action), and, further, to develop and implement programmatic social and economic solidarity rights: e.g. health, education, etc. The EU Charter, which was enacted with the ratification of the Treaty of Lisbon on 1 December 2009, opens a new chapter in the legal enforcement of solidarity rights, both at transnational and national levels.