Apart from the law the righteousness of God has been made known, to which the Law and the Prophets testify. This righteousness is given through faith in Jesus Christ to all who believe. There is no difference between Jew and Gentile, for all have sinned and fall short of the glory of God,and all are justified freely by his grace through the redemption that came by Christ Jesus.  (Romans 3:21-24)

The word translated ‘justify’ is δικαιόω dikaioo which is word taken from a legal setting, dike is ‘to be proved right’ or ‘to gain judicious approval’.  The word translated above as ‘righteousness’ as the noun based on the same root, δικαιοσύνη dikeaiosune.