-63The Committee is further concerned that new migrants are unable to apply for CSSA due to the seven-year residence requirement.” 178. Coming from no less a source than the CESCR, none of that is anything that an international financial centre (as Hong Kong is recognized in art. 109 of the Basic Law to be) can feel comfortable to read about itself. However that may be, the sufficiency or otherwise of benefit levels is not before the Court in this appeal. But what the CESCR says about the 7-year residence requirement’s adverse effect on new migrants is directly relevant in the present appeal, because it highlights the fact that the requirement excludes for a long time a large class which the relevant constitutional guarantees do not exclude at all. Retrogressive in regard to basic needs and deliberately so 179. Such exclusion is retrogressive. What makes it all the more serious is that it is retrogressive in regard to basic needs and deliberately so. In this connection, it is to be remembered that the CESCR had, on 14 December 1990, said this in its General Comment No.3, the reference for which is UN Doc E/1991/23, §9: “The principal obligation of result reflected in article 2 (1) is to take steps “with a view to achieving progressively the full realization of the rights recognized” in the Covenant. The term “progressive realization” is often used to describe the intent of this phrase. The concept of progressive realization constitutes a recognition of the fact that full realization of all economic, social and cultural rights will generally not be able to be achieved in a short period of time. In this sense the obligation differs significantly from that contained in article 2 of the International Covenant on Civil and Political Rights which embodies an immediate obligation to respect and ensure all of the relevant rights. Nevertheless, the fact that realization over time, or in other words progressively, is foreseen under the Covenant should not be misinterpreted as depriving the obligation of all meaningful content. It is on the one hand a necessary flexibility device, reflecting the realities of the real world and the difficulties involved for any country in ensuring full realization of economic, social and cultural rights. On the other hand, the phrase must be read in the light of the overall objective, indeed the raison d’être, of the Covenant which is to establish clear obligations for States parties in respect of the full realization of the rights in question. It thus imposes an obligation to move as expeditiously and effectively as possible towards that goal. Moreover, any deliberately retrogressive measures in that regard would require the most careful