Not sure how relevant this wikipedia entry is to the discussion at hand. Europe is not the United States of Europe. So you would have to look at the track record of each country's constituton. Looking at the three largest democracies in Europe, Germany, France and the UK, I'd say their systems have been a success. The UK are a bit of an odd one as they are a monarchy without a written constitution but a democratically elected parliament, and by extension Prime Minister. But all three countries have managed without civil war since their respective constitutions/forms of government have been established.