Injustice?

Views of Hindu traditions on karma
Scriptures divide Karma into three kinds: Sanchita (accumulated), Prarabdha (fruit-bearing) and Kriyamana (current) karma. All kriyamana karmas become sanchita karma upon completion. From this stock of sanchita karma, a handful is taken out to serve one lifetime and this handful of actions which has begun to bear fruit and which will be exhausted only on their fruit being enjoyed and not otherwise, is known as prarabdha karma. In this way, so long as the stock of sanchita karma lasts, a part of it continues to be taken out as prarabdha karma for being enjoyed in one lifetime, leading to the cycles of birth and death. A jiva cannot attain Moksha until the accumulated sanchita karmas are completely exhausted.

God is Omnipotent, Omniscient, and Just. Yet injustice is observed to persist in the world. How is this possible?
In the Advaita school of Vedanta, this problem is dealt with in detail by Sankara in his commentary on the Brahma Sutras, 2.1.34-36:
Brahma Sutra 2.1.34: "No partiality and cruelty (can be charged against God) because of (His) taking other factors into consideration."
Sankara's commentary explains that God cannot be charged with partiality or cruelty (i.e. injustice) on account of his taking the factors of virtuous and vicious actions (Karma) performed by an individual in previous lives. If an individual experiences pleasure or pain in this life, it is due to virtuous or vicious action (Karma) done by that individual in a past life.
Brahma Sutra 2.1.35: "If it be argued that it is not possible (to take Karma into consideration in the beginning), since the fruits of work remain still undifferentiated, then we say, no, since the transmigratory state has no beginning."
The opponent now argues that there could have been no "previous birth" at the very beginning of creation, before which Karma could not have existed. Sankara replies that it is not so, for the number of creation cycles is beginningless, vide the next verse:
Brahma Sutra 2.1.36: "Moreover, this is logical, and (so) it is met with (in the scriptures)."
Sankara provides references from the Vedas concerning the beginninglessness of Creation: "The Ordainer created the sun and moon like those of previous cycles" (Rig Veda 10.190.3). This shows the existence of earlier cycles of creation, and hence the number of creation cycles is beginningless.
Thus Sankara's resolution to the Problem of Injustice is that the existence of injustice in the world is only apparent, for one merely reaps the results of one's moral actions sown in a past life, which is compatible with the Justness of an Omniscient and Omnipotent God.
On the higher level of Existence, however, there is no evil or good, since these are dependent mainly on temporal circumstances. Hence a jnani, one who has realized his true nature, is beyond such dualistic notions.