SHAP. I] THE UNITY OF THE EMPIRE 1455 
On the other hand, the difficulties of this doctrine are very 
great internationally ; there can be but one nationality as 
long as the Empire remains united, and on what criterion 
could separate nationalities be devised within the Empire ? 
Is a New Zealander to be excluded from privileges offered by 
treaties to British subjects generally, and if so, what consti- 
tutes him a New Zealander? There are various criteria 
possible ; it might be birth, or residence, or domicile ; it is 
impossible to say that any one is a satisfactory basis on 
which to go, and in many cases there would be great doubt 
as to which was the proper principle. Yet, if no principle 
were framed, the plan could not work, while if residence or 
domicile were adopted as the line of division, a man might 
be often changing his nationality. It is indeed clear that 
allegiance to one Crown is the common bond, and that as 
nationalities there is no future for the conceptions of 
Canadian, Australian, &c., if these Dominions desire to form 
parts of the Empire. 
It is also clear that at the back of all the diversity of the 
Crown, which enables us to distinguish between the Crown 
in its various manifestations—so that the Crown in South 
Australia and the Crown in Victoria can engage in a dispute 
before the Courts as to the boundaries of the states in 
question, and the Crown in the states can be taxed in respect 
of its property by the Crown under the Commonwealth 
Parliament 1—there is a very real sense in which the Crown 
remains a single personality. In foreign affairs this unity 
is perfect; no foreign Power dreams of approaching a 
Dominion Government to demand redress or to ask for 
reference to arbitration. It is of course always open for 
a foreign Power through its consular representatives to make 
friendly requests to a Dominion, as for example with regard 
to immigration matters, which were dealt with in part direct 
* The King v. Sutton, 5 C. L. R. 789; Municipal Council of Sydney v. 
Commonwealth of Australia, 1 C. L. R. 208 ; The State of New South Wales 
v. The Commonwealth of Australia, 7 C.L. R. 179; and passim in C. L. R. 
The same principle has recently received emphatic approval by the Privy 
Council in The Dominion of Canada v. The Province of Ontario, [1910] 
A. C. 637. 
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