For as many as are lead by the Spirit of God, these are the sons of God (Romans 8:14).
The Christian does not need law because the Holy Spirit indwells him and he has been placed in Christ as a son. This new relationship and life enables the believer to act in a mature way—discerning what is proper from what is wrong by exercising his senses to know the desirous will of God in all situations, and, therefore, acting in a righteous manner by living out who he is in Christ.