If you act justly, you act in a way that is right or acceptable according to particular moral principles, such as respect for all human beings.
They were not treated justly in the past.
他们过去没有受到过公正的对待。
You use justly to show that you approve of someone's attitude towards something, because it seems to be based on truth or reality.
Australians are justly proud of their native wildlife.
澳大利亚人理应为他们本土的野生动植物而自豪。