The legal team led by David Lee successfully won a very important civil lawsuit for cross-category trademark protection for their client LEGO Group (a global leader in toys and gaming equipment products), effectively and cost-efficiently eliminating a targeted systematic and planned infringement and unfair competition.

In 2022, the LEGO Group discovered a company named "LEGO Sanitary" promoting its “乐高” and "LEGO" branded bathroom products online and using the "LEGO" trademark on toilets, which tarnished the "LEGO" trademark. In addition, the company registered domain names with "lego" as the main part and used “乐高” as its business name. Furthermore, the company applied for registration of more than 30 trademarks containing the words “乐高” and "LEGO", all of which were identical or similar to the LEGO Group's trademarks. The LEGO Group would have to spend a lot of time and cost to deal with these "brand-riding" trademark applications.

In 2023, acting on behalf of the LEGO Group, the Chang Tsi’s legal team filed a civil lawsuit with the Chaozhou Intermediate Court, asking the court to recognize the LEGO Group's trademarks as well-known trademarks and to provide cross-category protection. Chang Tsi submitted thousands of pages of evidence for the case. After the court hearing, the defendant agreed to accept Chang Tsi's settlement conditions under the court's persuasion, and the court issued a Bill of Mediation to close the case. Through the Bill of Mediation, the LEGO Group achieved all its objectives: first, it confirmed the LEGO Group's class 28 “乐高”, “樂高”, and "LEGO" trademarks as well-known trademarks; second, the defendant agreed to change its company name containing the word “乐高,” cease infringement, and deregister its domain name containing "lego"; third, the defendant agreed to pay compensation; fourth, and most importantly, it eliminated future problems. The defendant agreed not to apply for any trademarks identical or similar to those registered by the LEGO Group with the CNIPA in the future. If there was no settlement, achieving this goal of eliminating future problems would only be possible by initiating a separate complex lawsuit for unfair competition, which would require a lot of time and cost.