Mercy is beyond justice and love. It is a divine act. " to err in hunam but to forgive is divine"
Justice is a primary step where something good or bad is rewarded by good or bad respectively, this is what is done by the legal systems in our society. Love is beyond justice because here we love a person maybe without expecting anything in return. We maybe able to love Unconditionally with no selfish intention. But mercy is not as easy as love and Justice. It is a divine act of forgiving with full mind and consent to the particular person who has purposefully acted against you. ' Jesus face that got the father is merciful because he sends rain to the good and wicked alike'. Mercy is not something that a human can achieve it is a gift that is given to a person from above.