Dietrich Bonhoeffer in his book, Psalms: The Prayer Book Of The Bible, arranges the psalms into various division, including the Law.
Bonhoeffer describes understanding the law as "the entire salvation act of God and the direction for a new life in obedience. Joy in the law and in the commands of God comes to us if God has given the great new direction to our life through Jesus Christ."
Bonhoeffer continues, "It is grace to know God's commands. They release us from self-made plans and conflicts. They make our steps certain and our way joyful."