"There could be no effective control of the subject of immigration
if it were not possible to limit the entry and stay of
persons who claimed that they were only making a short
visit, or if it were not possible to deport persons who were
allowed into the country only for a specified period and who
then changed their minds and wished to remain permanently.
Immigration into a country, if completed, involves two elements,
(a) entry into the country, and (b) absorption into
the community of the country. Both of these elements can be
controlled under a power to make laws with respect to immigration.
It is unnecessary and somewhat unconvincing to
seek to justify legislation as immigration legislation upon the
basis of a contention that any entry into a country is 'immigration',
even though the entry is obviously only temporary.
Such legislation is justified as legislation upon the subject of
immigration because without control of the entry of all persons
not already members of the community there cannot be
control of the second element - possible absorption into the
community. Thus laws with respect to immigration may impose
conditions of entry upon such persons and may provide
for the limitation of the period during which they are to be
permitted to remain in Australia, and may lawfully provide
for their deportation upon the expiry of that period." (at p384)