The NPCSC decision has provided a strong constitutional and legal basis for the co-location arrangement.

Hong Kong. In Annex III, there are now 12 pieces of national legislation, including laws related to diplomatic privileges and immunities, nationality, the national flag and emblem, as well as PLA Garrison stationing in Hong Kong. These laws fall under the scope of “foreign affairs and national defense as well as matters outside the scope of autonomy”. Annex III lists no national law relating to customs, immigration and quarantine matters. Critics of the co-location arrangement argue that without invoking Annex III to add at least one national law relating to customs, immigration and quarantine control, it is not possible to implement the proposed co-location at the West Kowloon terminus. This argument reflects the differences between civil law and common law when dealing with matters related to relations between central and local governments.

Prominent mainland law professor Chen Duanhong emphasized that immigration matters fall under the scope of sovereignty matters from the views of the central government — who can leave or enter the mainland is a matter that may affect national security and foreign relations. Thus, for the question of whether or not national immigration laws can pass the test to be included in Annex III, the answer must be “yes”. However, there may be more than 10 pieces of national laws relating to customs, immigration and quarantine control.