Although baptised Catholic at birth and being sympathetic to German nationalism, he was suspended in 1933 under the Nazi Law for the Restoration of the Professional Civil Service, because of his Jewish ancestry.

He was reinstated later that year under the exemption for those who had worn the uniform of Germany or its allies in World War I, which had been insisted on by Weimar Republic President Paul von Hindenburg as a precondition before he signed the bill into law.

In 1935, he was dismissed once again under the provisions of the racist Nuremberg Laws; which led to his replacement as the Berlin Chair for Celtic Studies by Ludwig Mühlhausen [de].

He was the editor of the journal of philological studies Zeitschrift für celtische Philologie from 1921 until forced out by the Nazis in 1939,[citation needed] and was responsible for reviving it in 1954.

[8] Pokorny was a dedicated supporter of the Pan-Illyrian theory and located the Illyrian civilisation's Urheimat between the Weser and the Vistula and east from that region where migration began around 2400 BC.