THE aim of this policy is to strengthen the economic ties binding the countries of the British Empire together. Its supporters hold that the furtherance of Imperial Preference need not damage non-Empire trade; but it is difficult to imagine circumstances in which such injury would not arise. Theoretically one can imagine a condition whereby non-Empire trade remains stationary, whilst Empire trade increases; or that any decline in non-Empire trade is wholly due to causes unconnected with preference. But it seems probable that if Imperial Preference encourages Empire trade it does so at the expense of other trade. Whether this is a good thing or not is a matter of opinion, and forms the main bone of contention in this controversial subject.