Injustice includes taking another person's property without right, deceiving someone in a transaction, making a false accusation, and deliberately refusing a due right.
Consider two cases:
A borrower knowingly refuses to return an item despite being able to do so. This is a clear form of unfairness.
An item is accidentally lost despite appropriate care. This is not identical in intention or conduct to deliberately seizing another person's right; responsibility must be considered from the actual facts.
Judgment should rest on what happened, not on anger, rumor or a person's social position.