From its formation until the 1950s Labor and its affiliated unions were the strongest defenders of the
White Australia Policy, which banned all non-European migration to Australia. This policy was partly motivated by 19th-century theories about "racial purity" (shared by most Australians at this time), and partly by fears of economic competition from low-wage labour. In practice the party opposed all migration, on the grounds that immigrants competed with Australian workers and drove down wages, until after
World War II, when the
Chifley government launched a major immigration program. The party's opposition to non-European immigration did not change until after the retirement of
Arthur Calwell as leader in
1967. Subsequently Labor has become an advocate of
multiculturalism, although some of its trade union base and some of its members continue to oppose high immigration levels.