The Old Testament civil law is not unjust. According to the New Testament, it is just (Hebrews 2:2, 1 Tim. 1:8-11). But some Christians say it is unjust.
They trot out some laws they don’t like, and say they’re bad laws. I’ll admit some of the laws definitely seem foreign to us. But, rejecting them leads to some self-contradictions.
God gave the Jews the moral law, and almost all Christians believe it is sill binding on us today. The civil law, which some Christians dispute as to whether it still applies, is certainly consistent with the moral law. Bible-believing Christians can’t believe there are contradictions between the moral and civil law.
Since the moral law still applies today, you can’t say the civil law is unjust. That would mean there would be a contradiction between the moral and civil law. You have to believe that the civil law is just, even if you believe there are some range of laws that are now just. You can’t exclude the civil law from your range of just laws, or say it’s unjust, or point out laws you think are unjust.
If you think there are unjust civil laws, you’re saying there is a contradiction between the civil and moral law.
The truth is that the civil laws are the case laws of the moral law. They can’t contradict the moral law.
When you adopt an unbiblical idea, it inevitably leads to contradictions in your thinking.