With Beijing becoming increasingly assertive on issues of sovereignty and unity, the Hong Kong government will, like it or not, defend its red lines more vigorously. The education sector is a case in point. Seen by some as the cradle of opposition and defiance, it is under growing pressure to clean up its act before the authorities step in, as reflected in the lifelong disqualification of a primary school teacher in connection with perceived “pro-independence” learning materials. Officials are obviously keen to teach schools and teachers a lesson they think has been long overdue. However, the unprecedented move has not just raised questions on procedural justice, but also the boundaries of discussions and its possible chilling effect on wider academia. It is not surprising that social media has been flooded with comments critical of the punishment. From the material in question to the deregistration procedure, there is much support for the teacher concerned. While some say he did nothing wrong in using a documentary featuring Andy Chan Ho-tin, the founder of the now-banned pro-independence Hong Kong National Party, and other material to assist in what was said to be a discussion concerning freedom of speech, the authorities branded it as advocating separatism and banned him. Invalidating a professional qualification for life is a serious matter. The process must not only be fair and rigorous, but also be able to stand up in the event of a legal challenge. The decision was apparently taken despite an internal inquiry by the Kowloon Tong school concerned having cleared the teacher of any wrongdoing. The government only allowed him to explain his actions in writing, raising further concerns. An appeal is under way, and this may be followed by a judicial review. Hong Kong independence had no place in ousted teacher’s lesson plan: official The case dates from early last year, when the prevailing circumstances were very different. The sweeping national security law was yet to be imposed by Beijing and politically sensitive subjects could still be broached. In fact, it has been said the teacher only escaped prosecution because his actions occurred before the law was put in place. However, the lifelong disqualification still gives the impression that authorities have used the rules of today to punish him. That Hong Kong is an inalienable part of China is beyond question. But it does not mean the freedoms guaranteed under the Basic Law can be unduly compromised. How to draw the line between legitimate discussion and independence shall continue to be a matter of public concern. The last thing we want to see is different sectors shying away from politically sensitive issues.