As prime minister, Holt continued the liberalisation of immigration law that he had begun as Minister for Immigration. When he came to office, what remained of the White Australia policy was upheld by ministerial decree rather than by explicit legislation. In March 1966, the residency requirement for naturalisation was changed to a uniform five years; it had previously been 15 years for non-whites. Discriminatory provisions relating to family reunification were also removed. As a result, in the two years after March 1966 around 3,000 Asian immigrants were granted Australian citizenship, compared with 4,100 in the preceding two decades. Additionally, Immigration Minister Hubert Opperman announced that potential immigrants to Australia would be assessed solely "on the basis of their suitability as settlers, their ability to integrate readily, and their possession of qualifications which are in fact positively useful to Australia"; non-whites had previously had to demonstrate that they were "highly qualified and distinguished" to gain entry.