This paper aims to examine increases in professional liability for architectural and engineering (A/E) professionals following quantitative changes in litigation risks after the Chichi Earthquake. The methodology uses t-tests and ANOVA to analyse the impact of the earthquake with regard to (1) the number of A/E litigations, (2) the type of plaintiff, (3) court decisions, and (4) the scope of A/E activities or practices challenged by litigation. Our results showed the risk of liability lawsuits increased significantly, and lawsuits were more persistent after the earthquake. The professional liability risk seemed to intensify in higher courts. The risks of both professional liability and criminal indictment by public prosecutors were increased.