When combined, 正当 (zhèngdāng) acts as an adjective meaning “justifiable” or “legitimate.” It modifies the noun 防卫 (fángwèi), which means “defense” or “protection.” So, the term literally means “a defense that is justifiable.”
正当防卫 is primarily a legal concept defined in Article 20 of the Criminal Law of the People's Republic of China. For years, its application was interpreted very narrowly by Chinese courts, placing a heavy burden on the defender to prove their actions were not excessive. This reflected a cultural and legal preference for de-escalation and the maintenance of social harmony (和谐, héxié). Violence, even in self-defense, was often seen as a disruption to this order. However, recent high-profile cases have sparked intense public debate, leading to a gradual but significant shift. The courts have started to apply a broader interpretation, empowering ordinary citizens to defend themselves more robustly without fear of being charged with assault or “excessive defense” (防卫过当). Comparison with Western Concepts: A key difference lies in the contrast with American concepts like “Stand Your Ground” laws. In China, there is historically no legal duty to retreat, but the concept of proportionality is paramount. Your defensive force must be proportional to the threat. Using lethal force against an unarmed attacker who is merely pushing you would almost certainly be considered 防卫过当 (fángwèi guòdàng) - excessive defense, and you would be held criminally liable. The Chinese concept is strictly about repelling an ongoing attack, not preempting a potential one or retaliating after the fact.
While its roots are in law, 正当防卫 has found its way into modern, everyday language.
The connotation is generally neutral-to-positive, as it is a claim of justification. However, whether that claim is accepted depends entirely on the context.