According to a contract signed between Czechoslovakia and Hungary some 50 years ago, both nations are banned from introducing joint citizenship to the nationals of their neighbor.
Hungary stepped out of the agreement in 1993, however, the Slovakian side still considers it valid and effective.
The document stipulates that in line with the threats made by the Slovakian government, ethnic Hungarians applying for citizenship under the newly passed revision of the legal system would lose their Slovakian citizenship. This would naturally apply to their rights, like voting or the opportunity to hold certain state jobs.
It is difficult to judge whether the agreement in question is even applicable in the present conditions. Legal experts gave news portal [origo] greatly different answers depending on their nationality. (Origo)