Why are invalid patents not retroactive?

(1) Avoid the instability of executed judgments and rulings, which is not conducive to the stability of social and economic order. In addition, this arrangement can also avoid the institutional cost of restitution and save scarce dispute resolution resources (not wasting judicial resources).

(2) In most patent infringement disputes, the accused infringer often starts the patent invalidation procedure later, or defends by other means such as known technology, so as not to bear the tort liability. It is rare for a patent to be declared invalid after assuming tort liability. Therefore, maintaining the stability of executing judgments and related decisions will not lead to a large number of accused infringers, and this provision is also a reasonable choice after "two-phase balance".