Liberty is political freedom.  As members of the kingdom of God, we have the ability and the power to move about in the kingdom being a doer of the work and not a hearer only.  One of the greatest differences for me between being unsaved and born again into the kingdom of God is this concept of " the perfect law of liberty."  Before I was saved, I knew, in part, the good works to be done but did not have the power within me to perform them.  I was impotent to do the good works.  When I received the Holy Spirit at new birth, I received the power to become a son of God (John1:12).  This power is tantamount to receiving the ability to do the good works I was unable to perform in the old man.  To look into the "perfect law of liberty and to continue in it" is to hear the word of God and do it as a matter of habit...the habit of making the supernatural, natural in one's life.  We are saved unto good works (Ephes2:8-9) and James entire letter revolves around this point.  Salvation is an act of grace through faith unto works.  If we do not realize that our salvation was wrought to bring us to the place of efficacy in the kingdom of God, we miss the second point of our salvation.  The first is our being born into eternal life.  The second is being born to give birth to others, spiritually and physically.  So many in the body of Christ who are born again are so self-centered they fail to realize the social aspect of their redemption.  James goes on to further say that not only are we politically free (kingdom centered) but we will be judged by this law as well (James2:12).  If we use our wit to reduce our faith to confession without works, we deceive ourselves and the truth is not in us.  We are dead. (James2:26)  We have not the life of God living and active in us.  If we do what God asks us to do, we will have an anointing within us that will bear witness to the truth that we are children of God.  Judgment can be positive as well as negative.  When we go before God for judgment, not for our sins because they no longer exist, but for our works, it will be the perfect law of liberty that will be the judge.  We will be judged by the word and whether we yielded to the spirit of God or our own self(-ish) motivations. 
Kingdom spirituality implies that those in the kingdom take dominion over their domain.  Seeing others as a part of your kingdom and not as other and freely and joyfully giving of your time, treasure, and talents is what James is talking about here.  Kingdom spirituality is being generous with one’s stewardship of all that God has provided for us to enjoy.  What we think we possess is not ours, it is what God has given to us to both use and share.  Being led of the spirit of God, means that we do not fulfill the desires of the flesh but we see others as part of our kingdom.  We become other centered and God centered. We love God with all our hearts... and our neighbor as ourselves.
"The perfect law of liberty" is the freedom and power and privilege and right to bless others as God blesses us.  Let us look into this law and continue in it.  It will be confirmed by the anointing of the Holy Spirit in ways that we can not think or imagine.  To forget, having looked, is to forget what we look like after we have looked in a mirror.  Those who are born into the kingdom of God have seen what God requires as clearly as looking in a mirror.  They simply do not wish to act upon the influence of the Holy Spirit because of selfishness.  For those who ignore love, judgment will mean experiencing much less in eternity than what they could have had and that for all eternity.    "Be a doer of the work and not a hearer only" is the battle cry of James.   It is mine as well.

Amen