Historically, it was the principal legislative power in support of Australia's immigration scheme, which is now embodied in the Migration Act 1958 (Cth).
While the prosecution was pending, they were summoned to appear before a Board constituted under s 8A of the Immigration Act 1901–1920 (Cth) to show cause why they should not be deported from Australia.
The plaintiffs contended that s 8A was not authorised by s 51(xxvii) of the Constitution on five grounds, three of which concerned the content of the migration power.
Third, the Court adopted an expansive view of the power, holding that because the Parliament "had power to prohibit absolutely the entry into Australia of any person who is an immigrant," it could "prescribe the conditions on which an immigrant may be permitted to enter" (Knox CJ).
[1]: 552–565, 578 Starke J also drew on the history of British immigration laws in adopting an expansive view of the power.