Haha, I had trouble on this one at first, too. I've used different words; you're probably better off using these words instead to prevent confusion (i.e Equity and Equality)
Justice:
Justice is a complex concept. It varies between societies and individual concepts of what is just. Justice is more than fairness; it can be defined as when the right thing has been done.
Aristotle, the Ancient Greek Philosopher defined Justice into two catergories:
Corrective justice to redress a wrong (So like, correcting something).
Distributive Justice to ensure that everyone gets a share of society's goods.
(You might find that difficult to take in. So if you need to remember anything about Justice, just remember that it is "when the right thing has been done.)
Fairness:
Fairness is even more disputed than Justice. It can be defined as "free from bias, fraud and injustice". It usually applies to a particular situation or case.
Equality:
Equality can mean different things in different situations. It may mean equal treatments for everyone OR that treatment should vary according to the person's needs.
Example: Disabled car parking creates equality by giving someone an advantage.
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Okay so pretty much, a law can be equal without being just. For example,
Let's say that there's a speeding fine of $500 for anybody. Anybody. This means that it is equal because the outcome is equal for everyone (everyone must pay $500 if caught speeding). This law is not necessarily just though, because a millionare can easily pay the speeding fine. But what if it is a single mother with four children and low income? The outcome is not just because of her situation.
I hope that helped, guys.