Aliens Act 1 of 1937 was a South African law aimed at curtailing Jewish immigration to South Africa just as it was increasing due to increased anti-Semitic repression in Nazi Germany. The Act instituted an Immigrants Selection Board which would screen every potential immigrant coming to South Africa from outside of the British Empire or Ireland with the power to either grant or withhold a permit to enter the country. One of the qualifications the Board considered when assessing immigrants was "assimilability", a term not defined by the legislation and thus left to the board to interpret subjectively. "Unassimilability" was a criticism made of the Jews and thus its use as a criterion was seen as a pretext for excluding Jewish migrants.