There is a view that for an act to constitute conduct endangering national security, there must be evidence of force or violence. There are a few reasons why I disagree. “One country, two systems” is the policy that has underpinned the constitutional framework for Hong Kong since the handover, and it is guaranteed by both constitutional law and the Basic Law. A critical element of this policy is the protection of national unity and territory integrity. Freedom of expression is a fundamental human right, but it is not an absolute right and could be limited in certain situations. In the 1999 case of the government versus Ng Kung Siu , the Court of Final Appeal ruled that the principle of proportionality should be followed when an act of insulting the national and Hong Kong flags is deemed a crime. It was therefore lawful in that case to limit freedom of expression because the national and SAR flags represent the constitutional order established in Hong Kong under “one country, two systems”, and this order had to be protected against insulting behaviour. The Hong Kong National Party , which was recently outlawed for advocating independence for Hong Kong from mainland China, has pursued activities far more serious in nature than insulting flags, however. How Andy Chan’s ideas fail the test of common sense Each jurisdiction has its own standards in restricting certain speech and certain organisations. In Germany, for example, people are prohibited from displaying Nazi symbols and making the Hitler salute. It is also a crime to deny the Holocaust. China has been invaded by numerous foreign powers and still struggles to safeguard national unity and territorial integrity. Hence, the Chinese have taken great care to guard against any elements which may divide the country and endanger national security. In banning the National Party, the Hong Kong government has determined that the party’s speeches and activities are not mere political expressions and actually endanger national security. The party has pushed for Hong Kong independence through many channels: by taking part in legislative elections, publishing articles, fundraising, recruiting members and cooperating with overseas organisations. Hong Kong must respect ‘one country’ to keep ‘two systems’ Furthermore, the party has claimed many times that it will not exclude the possibility of using force or violence to achieve the goal of Hong Kong independence. It is hard not to associate this goal with secession, which poses an obvious threat to national security. Has the Hong Kong government gone too far in outlawing the National Party, even though there is no evidence of its use of blatant force or violence? Proof of force or violence need not be considered in some situations, like when state secrets are intentionally leaked. In the case of Communist Party (Nepeceriști) against the Romanian government, the European Court of Human Rights held in 2005 that if one organisation makes a public statement violating the principles of democracy, by calling for the use of violence or an uprising, it shall be restricted accordingly. Does separatist party ban threaten Hong Kong’s freedoms? The same court held in the case against the Basque nationalist political party Batasuna in 2009 that conduct endangering national security need not involve actual violence. An organisation can pose a viable threat to national security if it publicly calls for violence or has a relationship with a violent or terrorist organisation. Such an organisation can be banned, and Batasuna was outlawed. Consider the Hong Kong National Party in the light of these legal interpretations. Even though it has not used force, and its members have not carried guns and other weapons, it has spoken of an “armed revolution” and a willingness to achieve its goal of independence by any means. Furthermore, it has been linked to anti-China and pro-independence forces overseas, such as those advocating independence for Tibet and Xinjiang. Thus, the conduct of the Hong Kong National Party can be deemed to have endangered national security and the ban on the group is strongly justified. Gu Minkang is a council member of Chinese Association of Hong Kong & Macao Studies