The article discusses different ways to define public interest in constitutional law. It suggests three modes: letting the People's Congress decide case by case, giving the final say to the judiciary, or having the National People's Congress create laws to define public interest. The first mode seems impractical, the second is not justified, and the third is the best way to protect citizens' rights and limit state power. This approach has been successful in other places. Resolving contradictions in China's generalization of public interest is crucial for exercising state power properly.