Why do Hong Kong lawyers wear a wig-like hat when they go to court?

This is a feature of the common law system. Its symbolic meaning is: I am very old and my hair is gray, and I have enough experience to handle your disputes fairly, which is somewhat similar to the previous "patriarch". There is also a tradition in the countryside that whenever there is a dispute between neighbors, the old people and the most prestigious people in the village will be invited to mediate. That's why lawyers wear wigs