It is common in Spain to say that the Autonomous communities have the highest level of autonomy among the European Union: they have a lot of power in the areas of taxes, laws, etc.
I also heard about the Länder in German being very autonomous.
Having said that, how can such affirmations be done? Which patterns are used to sort this autonomy? Is there any index on this topic?
Finally, and based on hypothetical answers that may come, would my initial sentences be true regarding Spain and Germany?
Here's my view from the German perspective. I have no idea whatsoever about Spain, so maybe you'd need to discuss the points I give as examples for Spain in your own answer.
One point where the Länder are autonomous is education. Schools and universities are owned by the respective Land, and the curricula are set by the Land as well (they have a conference on that where all Länder try to agree on the rough guidelines, though). I put this first because it is a frequently told rumour that they will stick to this and not switch to more central and comparable curricula because this is the only field left where the Länder actually do have power to decide.
Each Land has its own constitution. The Länder would exist if the federal republic would decide to dissolve itself. However, there is a law that says "federal law breaks Länder-law", so the laws of the Länder can only refine federal law, or regulate things that are not regulated by federal law (e.g. education).
The responsibilities of Länder and federal republic are stated in the Grundgesetz ("federal constitution"). The basic rule is that the federal republik can only have responsibility (and legislative power) for topics that are assigned to the federal republik by the Grundgesetz.
That is, the Länder grant power to the federal republic AFAIK, the construction for the autonomous regions in Spain (and Italy) is the opposite: there, the state (= Spain, Italy) transfers certain rights to the regions.
Now, if we look at power:
Most of the police belongs to the Länder, the army is federal.
There are taxes owned by the federal republic (100 * 10⁹ €), taxes owned by the Länder and communal taxes (together 70 * 10⁹ €), and "mixed taxes" (425 * 10⁹ €) (2012 numbers, source: federal statistics office). Of the mixed taxes, slightly less than half is federal, a bit less goes to the Länder, and a small part is communal.
All in all, all Länder together have a bit less money than the federal republic.
I'm not aware of any index for the comparison of autonomy within EU regions. There are studies such as Europe's Working Regional Autonomies - A Comparative Analysis by Thomas Benedikter. See also The working autonomies in Europe and The World's Working Regional Autonomies.
Notice that there is a difference between Regionalism (see also Unitary States) and Federalism. I don't think it would be fair to compare Germany (a federation much like the European Union) to a Unitary State such as Spain (and by consequence its administrative regions). In fact you'll probably never see the German regions ever being considered in any list of autonomous administrations.
That being said Benedikter has used criteria such as legislative, financial, executive powers, political representation among others to make the comparison. The Spanish communities are indeed very autonomous by European standards (and likely by World). They are not, however, the regions with highest level of autonomy. Quoting Benedikter:
Considering the whole range of these ten autonomy systems in Europe under the above listed criteria it is possible to form a first ranking focusing on the real depth and extent of self-governance. Of course this evaluation scheme is a very rough and provisional, but it should just help us to understand that, due to political, historical and social background, autonomy systems have developed differently and are a flexible means to solve different problems.
He considers:
The Ålands Islands detain the most complete and far reaching autonomy. Under the Act of Self-Government of 1991 the Ålanders enjoy legislative and executive powers in nearly all political sectors which matter for the peoples on the islands.
As for the specific case of Spanish regions:
Also the Spanish autonomous communities, and in particular the autonomy systems of the historical "nationalities" of the Basques, the Catalonians and the Galicians, can be qualified as comprehensive autonomies with legislative and executive powers in nearly all internally relevant political affairs and a government which is responsible only to the regional autonomous parliament. They have not only budgetary autonomy, but clear-cut powers of taxation, shared with the central state. Spain's autonomous communities have their own civil and administrative judiciary, but the Basque Country and Catalonia have even their own police force. The Spanish autonomous communities are also vested with a competence normally reserved only to federated member states of a federalist union, the power to elaborate their own autonomy statutes. The amount of autonomous powers of a region in Spain is in a high degree up to the region itself which, within the constitutional framework, can freely regulate its own autonomy. Hence, Spain's regional autonomies are continuously extended and improved. However the autonomy statutes have to be approved with simple majority by the central parliament of Madrid.
So your quote:
... the Autonomous communities have the highest level of autonomy among the European Union
Is perhaps an exaggeration but not far from the truth. Also notice that there are differences in between different regions of Spain.
