The test to be applied in each instance should be the balance of interest involved, including a strong public interest in standardization as one of the elements in a policy of wage settlement. When weighing the facts for or against the limitation or variation for the reason under discussion, several distinctions should be made. Firstly, in regard to the nature of the difference in advantage possessed by the various units of the industry in question. Secondly, in regard to the way in which the differences in advantage are distributed among the various units of the industry. The case for limitation or variation is apt to be stronger when the difference in advantage is a natural difference than when it is an acquired difference. In either case, the decision must rest upon the balance of good and harm to be anticipated from a straightforward and unmodified application of the principle. But when the difference in advantage is a natural difference, such as exists between different mining areas, there is greater reason for deliberate procedure than otherwise. For the possibility that an abrupt suspension of certain enterprises be caused without compensating extension of other enterprises, is the more genuine. Such a situation was recognized, for example, in the case of the living wage legislation for agriculture in England; and thus instead of applying one standard wage throughout all districts, standardization was carried out by districts.[87] Even in this case, however, the various district advisory boards are under a strong and constant pressure (under the terms of the act) to bring the rates in the various districts to the same level. Such, also, to take another example was the situation recognized in the course of the attempt during the war to standardize the wages of the stevedores and longshoremen employed in the South Atlantic ports. Here straightforward and unmodified standardization would have caused, it was judged, the diversion of certain freight carrying steamship lines from ports in which they now operate. If the differences in advantage are in the nature of acquired differences, only convincing evidence of the permanent harm likely to result from general standardization would justify limitation or variation. For in this case, the necessity of paying standard wage rates is itself a powerful force towards overcoming conditions that have been declared a definite competitive disadvantage. Probably no extension of wage standardization in industry has ever taken place without injuring some individuals. It is the net balance of gain or loss that is significant. In most past instances when standardization has been enforced in an industry, marked by an unequal distribution of acquired advantages, the consequences have not verified the predictions of those who believed it would cause great disturbance and unemployment. On the contrary, it has frequently resulted in the development of better organization within the industry.