Recently an issue concerning whether the Hong Kong Special Administrative Region (HKSAR) has a power of sub-sovereignty has been raised by the local media in regard to Chief Executive Donald Tsang's direct call to Philippine President Benigno Aquino on August 23 when Hong Kong tourists were being held hostage in Manila. Someone argues that Mr Tsang, who is of much lower rank than the head of State of the Philippines should not contact Mr Aquino according to diplomatic protocol. Some defends the point, arguing that in an emergency everything is possible and rational. Others assert that the chief executive does enjoy a power of sub-sovereignty.

Only on grounds of urgency, can the argument be sustained.

By virtue of International Convention against taking hostages, the cooperation with goodwill among all stakeholders shall not be regarded as a matter of pure diplomacy. Manila might telephone Beijing or/and Hong Kong and vice-versa. In respect to this kind of conduct, I believe the use of a pre-mature concept of sub-sovereignty is unnecessary.

In addition to cases of urgency, the head of the HKSAR is authorized to exercise a high degree of autonomy (also as a separate customs territory) under the Hong Kong Basic Law. Thus he may call the head of another separate customs territory like the Philippines or Russia or other equivalents notwithstanding that there may not be any direct diplomatic link.

To make efforts for the release of the captured hostages in a foreign state is no doubt a diplomatic affair as defined in Article 13 of the Basic Law to be the responsibility of the Central Government, but this should not be interpreted so as to preclude the responsibility of the HKSAR under Chapter 7 entitled "external affairs" as far as the Hong Kong tourists are involved.

Is this arrangement logical? Yes, of course. It is not unusual that one thing can fall into more than one category for the good of the people. Hong Kong residents will certainly be happy if their safety in foreign countries has been attended by two governments instead of one. One is the Central Government, the other is a local government, under the proper authorization from the former.

Regardless that the idea of so called sub-sovereignty may or may not be accepted in academic circles, it is neither popular, nor agreeable, nor recognized in International Law. There is no such expression in any legal document in International Law available to us, nor in any legal document in Domestic Law in both federal and unitary States. The word sovereignty means the supreme authority in an independent political entity (nation).

In a federal state, the power of the supreme authority can be separated or divided by its constitution between the federal government and local(state) governments; but the said power can not be separated nor divided in a unitary state between the central government and local governments. The People's Republic of China is a unitary state. Its sovereignty can be exercised only by the Central Authorities as defined in the Constitution. The power enjoyed by the HKSAR is, however, called a high degree of autonomy authorized by the Central Authorities rather than sub-sovereignty.

As to the call itself, it is said that Mr Aquino called Mr Tsang back the next day. This implies Mr Aquino's recognition of his obligation to return the call, though his position differs from that of Mr Tsang no matter there is sub-sovereignty or not.

The author is a current affairs commentator, PhD in Law.