The treaty was intended to bring diplomatic and economic stability in western Europe after the Second World War.

The Declaration emphasised that the supranational principle was the foundation of the new democratic organisation of Europe.

Since the end of World War II, sovereign European countries have entered into treaties and thereby co-operated and harmonised policies (or pooled sovereignty) in an increasing number of areas, in the European integration project or the construction of Europe (French: la construction européenne).

The following timeline outlines the legal inception of the European Union (EU)—the principal framework for this unification.

The EU inherited many of its present responsibilities from the European Communities (EC), which were founded in the 1950s in the spirit of the Schuman Declaration.