The 1986 Single European Act was the first major revision of the Treaty of Rome that created the European Economic Community in 1957. The Act meant a commitment of joint progress, and a new manner of coordinating economic activities, after the failure of semi-plannified economy and the collapse of the Bretton Woods system (dependent on the dollar) that happened during the 70's.
The result of the Act was the creation of the European Monetary System (called "of the European snake in the tunnel", as European currencies were floating in group against the rest). This was the first step to the arrival of the euro economy.
Another wanted step was the administrative reform of the recently named European Union, which was becoming more and more complex when taking joint decisiones (the system of national vetoes made agreements very long or impossible).
However, no political topics were treated (the absence of a common Defense and Foreign Affairs) nor many economical (such as the aberrant agricultural budget applied since the entrance of Spain and Portugal). But the countries agreed on one thing: reaching a free market of goods and work.
So, the decision-taking system was almost only economic. In order to ease it, the national agreement system was switched into another one in which regions had direct access to the European Council in Brussels and could act independently from their corresponding national entity. The Europe of the Regions started existing.
A new imbalance
The result was a modification of budget decisiones taken by the European Regional Development Fund (ERDF), which identified backward European regions and distributed investments in order to estimulate their economies. Now regions avoided their Governments, not generally very willing to cooperate in regional investments. Some of them, generally the richest (such as Catalonia and Baden-Württemberg), established their own offices in Brussels to constitute true lobbies.
Consequence? The richness desequilibrium was not reduced (rather the contrary), but it was redistributed by regiones instead of countries. Now, a group of first order regions existed (Lombardy, Catalonia, Flemish Region, Baden-Württemberg, Bavaria, Rhône-Alpes...), and another group of poor ones (Andalusia, Scotland, Wallonia, Algarve...). A new, costly bureaucracy, that did not doubt when manipulating subsidy data, intensified the problem.
In conclusion, Europe, without solving its old defects of clientelism and corruption, just diluted them into a new structure where abuses still often happened. Economic rforms based in the 50's and 60's way of thinking (already shown inefficient) unlegitimated a bit more a Union that, nowadays, is clunking and needs real measures.
Definitely, it was successful in one thing: the appearance of a new way of regional sub-nationalism. It is not a coincidence that in the most subsidied European regions, this regionalism passed from a traditional reactionary folklorism to a conscience, sometimes independentist, in which a disdain towards governmental identity, but also an Europeist supra-national thinking has invaded their inhabitants.