What is the Female Sentencing Discount?

IMO all jail sentences are inadequate for anyone and any crime. If the study showed that gender is a factor in sentencing then what's the point of having a legal system that is unfair and biased? It's against the very meaning of law. Being a woman is not an excuse for crimes that should carry heavy sentences. Do the crime, do the time. Does the study offer any suggestions as to how the legal system can be overhauled to account for these inconsistencies?