The judge ruled that his actions were in self-defence as his life was in immediate danger.

self-defence 是由 self（自己）和 defence（防卫、防御）组成的复合名词。 self 表示"自己、自身"的意思。 defence 是名词，来自动词 defend（防御、保护），指"防卫、防御的行为或措施"。 self-defence 指"为了保护自己免受伤害而采取的防卫行为"，在法律上特指"正当防卫"。