"The scene that Luther sketches is so clear; the person stands accused, but the roles are reversed. The judge takes on the defense and the accused becomes the accuser. This is what God's righteousness means!
The verdict that God pronounces stands on the side of man, right next to him and in front of him, and lays righteousness between sin and the person like a chasm. We are raised up, buried, protected, and guarded in Jesus Christ in whom we die in order to live and in whom we find ourselves created new: true, righteous, pure, free, good and holy."
--- from The Righteousness of Faith According to Luther by Hans J. Iwand