The winner was disqualified for cheating, so justice was done.

justice 是名词，来自形容词 just（公正的），加上名词后缀 -ice 构成，表示"正义、公正"。 justice was done 是一个固定表达，字面意思是"正义被执行"，引申为"正义得到伸张"或"公道得以实现"。