As stated in the Hong Kong Basic Law, the SAR is an inalienable part of the People's Republic of China. It is a local administrative region that enjoys high degree of autonomy but is directly under the jurisdiction of the central government.

Thus speeches that advocate Hong Kong independence may be treason or sedition under the under Hong Kong Crimes Ordinance. Hong Kong's Societies Ordinance also stipulates the principle of "no violation of national security, public security and public order" in the process of registration and operation of societies.

This is why so-called parties that advocate Hong Kong "independence" cannot be legally registered in Hong Kong.

"Hong Kong independence" speeches and behavior are a "clear and present danger". They not only undermine the principle of "One country, Two Systems", but also threaten national sovereignty and national interests. In addition, they also undermine Hong Kong's prosperity and may cause social disorder.

The principle of "One country, Two Systems" is the basic policy by which the central government deals with Hong Kong issues. "One country" is the precondition of "Two Systems", and without the basis of "One Country" there can be no "Two Systems".

In the context of "One Country, Two Systems", these groups advocating Hong Kong's "independence" and seeking to make Hong Kong a city state, pose a great danger to national unity and territorial integrity.

And their illegal words and actions not only deal a blow to the order of Hong Kong society and ruin the lives of other residents, they also tarnish the image of Hong Kong as a city that is proud of its rule of law.

The author is a professor of law at Peking University.