When the Nazis came to power and Adolf Hitler was appointed chancellor on January 31st 1933, an authoritarian regime was put in place in Germany, and was responsible for one of the most tragic events in human history.
The Nazis banned parties, persecuted opponents, and deprived people from their citizenships on racial, religious, and political grounds. They reserved to themselves the absolute right to determine who could be a German citizen.
Through a decree signed in 1935, Adolf Hitler revoked the article 31 of the Nationality Law of 1913, and thus deprived former Germans affected by the old consular registration requirement to re-acquire their citizenships.
Law for change of the Reich and Citizenship Act.
15 May 1935.
The Reich government has passed the following law, which is hereby announced:
§ 1 The naturalisation authorities decide on the granting of German citizenship at its discretion. There is no entitlement to naturalisation.
§ 2 Sections 10, 11, 12, and Section 26 (3) sentence 2, Section 31 and Section 32 (3) of the Reich and Citizenship Act of July 22, 1913 (Reichsgesetzbl. I p. 583) expire; the same applies to section 15 subsection 2 and section 34 insofar as they grant a right to naturalisation.
§ 3 The law comes into force on the day of its promulgation. 
Berlin, May 15, 1935.
O Führer e o Chanceler do Reich Adolf Hitler
O Ministro do Interior do Reich Frick
Hitlers and the nazis gained full power through the Enabling Act of 1933. This law allowed the regime to enact new laws even if they violated the constitution, without the need to obtain the approval of the president and the Reichstag. The original name of this law in German is: “Gesetz zur Behebung der Not von Volk und Reich”, which translated to English means: “Law to Remedy the Distress of People and Reich”.
The way the Enabling Act was passed is extremely controversial and is directly linked to the Reichstag Fire Decree of February 28th, which the Nazis had already used as pretext to revoke civil liberties, press freedom, and to arrest opponents without due legal process. As a result of this decree, the Communist Party was banned and many Social Democrat representatives were prevented from voting against the new Act, allowing the Nazis to reach the two thirds of votes needed.
In the aftermath of WWII, the Enabling Act was promptly revoked by the Allied Control Authority through the Control Council Law No. 1 on September 20, 1945. Most nazi laws were revoked explicitly by this law, among them all of which had deprived German Jews from their citizenships. When the Federal Republic of Germany enacted its new constitution, the removal of all nazi laws were again confirmed.
Unfortunately the nazi decree of May 15th 1935, signed by Hitler, which had deprived former Germans affected by consular registration of their rights was never revoked, and the article 31 ever restored.