Citizenship by itself is much more complicated than it may sound to many. The difference between citizenship, nationality, origin, etc. may be hard to define, especially in international law.
The Bulgarian Constitutional Court about the citizenship of Mr Kiril Petkov
Recently, a controversial legal dispute started with regard to the citizenship(s) of Mr Kiril Petkov (ex-minister of economy). The Bulgarian Constitutional Court has started legal case and it will soon rule whether the presidential decree to appoint Kiril Petkov as minister of economy has violated the Constitution or not.
With regard to the case, Mr Yanaki Stoilov, minister of justice, was requested by the Constitutional Court to send confirmation as to whether Mr Petkov has been Bulgarian citizen at the moment of his appointment as minister of economy. You can read very interesting legal analysis about the letter that Mr Yanaki Stoilov, in his capacity of minister of justice, has sent to the Constitutional Court.