Chau is also the lead prosecutor for the 2019 Yuen Long attack. In February 2021, judge Eddie Yip expressed frustration with Chau, who repeatedly complained that Chau glossed over important details, such as who started the attack; Chau eventually admitted that those in white were the ones who started the attack. The judge also complained that Chau's timeline of events felt like an "edited film" and was confusing. Chau also described the incident as a "physical collision," to which the judge remarked "What does 'physical collision' mean? Playing bumper cars?"