Persons of Russian, Belarusian, Ukrainian, Lithuanian, Latvian or Estonian nationality.

Pursuant to the Act of January 9, 1951 on Polish Citizenship, upon entry into force of this Act on January 19, 1951, persons of Russian, Belarusian, Ukrainian, Lithuanian, Latvian or Estonian nationality. who, on August 31, 1939, had Polish citizenship, but lived permanently abroad, lost Polish citizenship.
The main purpose of such regulation was, of course, depriving Polish citizenship of persons permanently resident in the USSR who were not of Polish nationality. However, it should also be noted that the Act also deprived Polish citizenship of emigrants, e.g. in the USA or Brazil, if it turned out that they were not of Polish nationality.