Abstract:      Strengthening patent judicial protection is to encourage innovation, and it is an important topic to discuss whether patent litigation can promote technological innovation of enterprise in the field of patent management research. The existing literatures mainly examine the effect of patent litigation on enterprises′ R&D investment and number of patent applications, ignoring the changing trend of patent quality after patent litigation. This paper takes the foreign-related invention patent civil cases from 2000 to 2018 as a sample, and constructs a dynamic effect model to examine the differences in technological innovation decisions of defendants after the lawsuit was involved from the perspective of scale. Moreover; we use multiple indicators such as the number of claims, the width of patent protection, and the width of patent knowledge to describe the trend of changes in the quality of patent applications after patent litigation to ensure the reliability of the model. 
    In terms of the amount of infringement compensation, the amounts of compensation for foreign-related patent litigation cases are higher than that of domestic patent litigation cases. The average value of the actual compensation for foreign-related patent cases that published from 2000 to 2018 reached 420,000 Yuan. From the perspective of litigation strategy, foreign-related patent litigations present the characteristics of combined litigations and multiple litigations. More than a quarter of foreign-related invention patent cases are patent combined litigations, half of which are multiple litigations. From the perspective of the parties involved in the lawsuit, 80% of the enterprises that have applied for invention and utility model patents are small and micro enterprises. These characteristics of foreign-related patent litigations make the technological innovation decisions-making by Chinese defendant enterprises present the characteristics of heterogeneity of scale and heterogeneity of innovation ability after the lawsuit is involved.
    The empirical results show that: (1) Foreign-related patent litigation will improve the quality of patent applications of Chinese defendants, and which has a more significant positive effect on the quality of patent applications of large and medium-sized enterprises; (2) Different from the changes in the quality of patent applications, the number of patent applications by small and micro enterprises has increased significantly after the acceptance of foreign-related patent litigation, while the impact of foreign-related  patent litigation on patent applications of large and medium-sized enterprises is not significant; (3) Considering the heterogeneity of innovation capabilities, the number of patents applications by small and micro enterprises after patent litigation shows an inverted U-shaped growth relationship. Small and micro enterprises with a weak innovation foundation are more active in patent applications after patent litigation, owing to the impact of economic efficiency; they would choose to give up improving the quality of patent applications from the fifth year after the lawsuit is closed. After controlling for endogenous influence and selection bias, the empirical estimation results are still robust.
    According to the research conclusion and the actual situation, we put forward two policy suggestions on how to improve enterprises innovation capabilities and patent quality: (1) Introducing patent quality-oriented policies, building a number of high-quality patent cultivation centers and further improving intellectual property financial service innovation to support small and micro enterprises; (2) Continuing to promote the construction of intellectual property courts and local intellectual property courts, improving the standards and calculation methods of intellectual property infringement compensation, and further stimulating the enthusiasm of enterprises for technological innovation.

Key words:  foreign-related patent litigation, enterprise scale, technological innovation, patent application, patent quality