1.

King gives a few tests. At the core, a just law is a human-made code that squares with the moral law, or the law of God, and that “uplifts human personality,” while an unjust law is out of harmony with the moral law and “degrades human personality.” Beyond that moral standard, he offers a practical way to tell them apart: a just law is one that the majority is willing to follow and applies equally to itself, whereas an unjust law is one that a majority forces on a minority without binding itself to the same rule. He adds that a law is also unjust if a minority had no part in creating it because they were denied the right to vote or otherwise shut out of the process. So the difference comes down to whether the law is applied equally, whether the people bound by it had a voice in making it, and whether it dignifies or degrades the people it affects.

2.

I think it’s an important distinction. It matters because it gives people a principled way to decide when obeying the law is a moral duty and when resisting it is. Without that line, “it’s the law” becomes an excuse to accept anything, no matter how harmful — which is exactly the trap King warned about when he criticized people more devoted to “order” than to justice. On an individual level, it shapes whether someone speaks up or stays silent. On a societal level, it’s the foundation of civil disobedience, and almost every major reform movement in American history — abolition, women’s suffrage, the civil rights movement itself — depended on people deciding a law was unjust and acting on that. It absolutely affects our politics, because how we define “unjust” determines which protests we see as legitimate and which we dismiss, and that disagreement is at the heart of a lot of political conflict today.

3.

An example of a just law would be laws requiring equal access to public accommodations under the Civil Rights Act — no one can be turned away from a restaurant, store, or hotel because of race. By King’s standard it’s just because it applies equally to everyone, protects human dignity, and uplifts rather than degrades.

An example many would argue is an unjust law would be certain voter ID or felony disenfranchisement laws. Using King’s own test, a law becomes unjust when it burdens a minority that had less voice in shaping it, and when it isn’t applied equally in practice. if a rule falls much more heavily on one group and effectively strips them of a say in the laws they live under, it fits his description of a code that a majority imposes on a minority without binding itself in the same way.