Open access to the internet is what makes Hong Kong an attractive place in China to do business, work and live for many people. It is why the United States’ online giants have a presence in the city rather than on the mainland, where they are generally banned or blocked. But the introduction of a national security law in Hong Kong has given them pause for thought, their platforms being about the free flow of information. If any determine their users have more to lose than gain through their presence and decide to quit the city, there are likely to be local reputational consequences. That is not to contend that firms such as Google, Facebook and Twitter and apps including WhatsApp, Instagram and Telegram should be above the law. They cannot be allowed to carry information that violates rules, is discriminatory, false or harmful to others. They usually state such matters in their regulations and expect users to follow them or risk having accounts closed. The problem for many Hong Kong people familiar with the common law system is that the legislation’s unclear language and broad provisions make for uncertainty about what constitutes a violation. Refusing to cooperate with Hong Kong police a ‘real risk’ for social media giants TikTok is not taking chances; its video-sharing app is no longer available to Hong Kong users . But the firm is in a difficult position, being Chinese-owned and accused by some people of sharing data with Beijing, an unproven claim. The move is an apparent effort to protect its overseas market share. India recently banned the app and US President Donald Trump has indicated his administration is also considering outlawing it. Pulling out of Hong Kong would be seen as sending a message to users that it is protecting their information, even though there is as yet no suggestion that authorities have any intention of targeting the firm or its counterparts. It also has a backup strategy in that it has a similar product on the mainland that is available in the city. Facebook, Google, Microsoft, Twitter and Zoom are among US internet firms that have announced they are suspending the processing of requests for user data from Hong Kong authorities while they study the new law. The legislation requires them to hand over such information if requested to; some have previously been complying. This is a testing time for foreign firms in general and especially those from the US, with Trump’s administration having imposed sanctions on Beijing and local officials for introducing the legislation. Apart from how to interpret the new law, they have to decide whether to side with Beijing or Washington. All internet companies, local and foreign, have to fully abide by the law. But authorities also have to ensure that their requests for protecting national security are fair and reasonable.