Hong Kong officials have frequently reminded us of the importance of obeying the law, since the Occupy civil disobedience movement saw thousands take to the streets three years ago. The city has long enjoyed a reputation for being a lawful and orderly part of the world. It is not surprising that the only duty imposed on Hong Kong people by the Basic Law , the city’s de facto constitution, is to obey the law. But if we are to regulate our behaviour according to the law, we need to know what the law says. And that is not possible if the law in question has not yet been passed. Recent suggestions that a forthcoming law which will make it a crime to disrespect China’s national anthem might operate retroactively are, therefore, a matter of concern. China’s law on the national anthem is expected to be applied to Hong Kong by the National People’s Congress Standing Committee this weekend. But it will not have legal effect in the city until a law has been passed by Hong Kong’s legislature. Time will be needed for the legislative process to take its course. Given the disgraceful booing at Hong Kong football matches, we can’t wait any longer for a national anthem law For some, the law cannot come quickly enough. Hong Kong football fans began booing the national anthem at matches around the time of the Occupy protests. At a recent match at Hong Kong Stadium, some fans not only booed but turned their backs to the pitch and held up pro-independence banners. This may be offensive and disrespectful. It may lead to the Hong Kong Football Association being fined by Fifa, the sport’s governing body. But it is not a crime. Under Hong Kong’s existing laws, this is a lawful form of expressing discontent. Don’t boo Chinese national anthem, Hong Kong football authority begs fans Rao Geping, a law professor at Peking University and adviser to the NPC Standing Committee, has suggested Hong Kong officials keep a register of people who boo the national anthem with a view to punishing them once the new law is in place. Rita Fan Hsu Lai-tai, Hong Kong’s representative on the Standing Committee, has warned that the national anthem law might be applied retroactively if democrat lawmakers delay the passing of the relevant legislation in Hong Kong by filibustering. Such calls should be resisted. Retroactive criminal legislation is prohibited by the International Covenant on Civil and Political Rights, which applies to Hong Kong through the Basic Law. There is a similar provision in the Hong Kong Bill of Rights Ordinance . Such laws are not permitted in the city. The Court of Final Appeal, ruling on immigration legislation in 1999, found part of it to be unconstitutional because it was retroactive. Hong Kong could apply national anthem law retrospectively, but should it? Chief Executive Carrie Lam Cheng Yuet-ngor , when asked about the national anthem legislation, pointed out that Hong Kong does have some laws which operate retroactively. She referred to the imposition of a higher stamp duty on residential property in November last year. The law underpinning the increase has not yet been passed. But the two laws cannot be compared. The national anthem law is expected to create criminal offences potentially leading to imprisonment for offenders. It is very different to an increase in stamp duty. The principle that laws should not work retroactively has existed for hundreds of years. It is to be found in the writing of English philosopher Thomas Hobbes and the French Declaration of the Rights of Man in 1789. Today, the rule is widely accepted around the world and is found in numerous constitutions and human rights agreements. While there have been occasions when the common law has recognised retrospective legislation, criminal laws which operate in this way run counter to Hong Kong’s rule of law and breach the Basic Law. Secretary for Constitutional and Mainland Affairs Patrick Nip Tak-kuen has said that it is unlikely the national anthem law will be applied retrospectively. That is good to hear, but any possibility of this happening should be swiftly ruled out. Certainly, it should not form an option in any public consultation on the proposed law. Hong Kong is a city governed by law. But no one should be punished for breaching a law before it has been passed. Cliff Buddle is the Post’s editor of special projects