When to capitalize "European":
* As part of a proper noun:
* Countries: European Union, European Economic Area
* Organizations: European Parliament, European Commission
* People: European Americans, European Canadians (when referring to a specific group)
* Specific events or movements: European Renaissance, European Enlightenment
* As an adjective before a proper noun:
* European History, European Parliament
When not to capitalize "European":
* As a general adjective: European countries, European culture
* As part of a common noun: a European, Europeans
* When referring to the continent in general: Europe is a large continent.
Example:
* Correct: The European Union is a political and economic union of 27 member states.
* Correct: The European Parliament is the legislative body of the European Union.
* Correct: Many European countries are members of the NATO alliance.
* Correct: He is a European who lives in France.
In summary, capitalize "European" when it's part of a proper noun or used as an adjective before a proper noun. Otherwise, use lowercase.