The constitutional controversies that have troubled Hong Kong since the handover underline the need for a good understanding of the law. Legal issues have dominated the debates on sensitive issues such as the right of abode, new national security laws, political reform and the length of the new chief executive's term. After each of these controversies there have been calls from officials on both sides of the border for the public to develop a deeper knowledge of the Basic Law. It has also been argued that a better, smoother way must be found to resolve such disputes. A solution is not easy to find. But it is clear that legal experts and their research into these issues have an important part to play. It is therefore sad to learn that eight legal scholars are leaving the University of Hong Kong. Most are prominent figures with rich experience in the field of constitutional law and human rights. Professor Yash Ghai, for example, is an internationally renowned constitutional expert and a leading authority on the Basic Law, and associate professor Carole Petersen helped draft bills concerning Hong Kong's equal opportunities laws. Professor Roda Mushkat has been at the university for 26 years. All have made a significant contribution. They are leaving for different reasons. Some have reached the university's relatively low retirement age of 60. Others are moving because of family commitments or to take up jobs overseas. But their departure will, within a relatively short time, deprive Hong Kong of a wealth of expertise and talent. Their voices will be missed when important legal issues are debated in the future. It is vital that Hong Kong's law schools are able to attract top legal brains from around the world - especially in the area of constitutional law. Their broad experience and the insight they offer into complex legal issues is invaluable. Experienced international experts are needed to carry out the research that will help develop our understanding of the law. They are also well-placed to inspire and nurture future generations of lawyers and legal academics for Hong Kong. In this way, the reputation of our law schools will grow. There are suggestions that perceived restrictions on academic freedom are making it more difficult to attract top legal experts from overseas. If such a perception exists, it needs to be dispelled. Our academics are free to conduct independent and objective research. That is precisely what is required. The law faculty has recognised the contribution made by the experts who are leaving. It points out that this will create new opportunities for younger members of staff. A certain amount of fluidity is certainly healthy. But it is important to strike the right balance between academics with long experience and those who are still carving out their reputations. The good news is that the university has already found replacements for some of those who are leaving and intends to replace the others. There had been speculation that Yash Ghai's position as a chair professor would not be maintained after he had gone. But the post has been advertised - and a successor is being found. Lyal Sunga, who runs a key human rights law programme, is to be replaced by an experienced candidate. The dean of the law faculty, Johannes Chan Man-mun, has pledged to aim for four chair professor positions to strengthen the faculty. That should certainly be pursued. Usually, such posts are filled by distinguished academics whose work is recognised around the world. There is a need for Hong Kong to be competitive in acquiring world-class talent in all academic fields. But the importance of the rule of law and the constitutional problems the city has encountered means that the demand for top legal experts should be particularly strong. The departure of the eight legal experts leaves a hole. It must be filled in a way that ensures Hong Kong maintains the same level of experience and expertise.