Since the Major Arcana do not apply directly to physical life, it must follow that Justice does not apply to the laws made by mankind. True, sometimes the laws of mankind mimic the laws that Justice does enforce, and in those rare cases Justice can indeed refer to them. But Justice typically refers to the immutable laws of the Universe, the invisible principles that keep everything flowing forward smoothly through infinite causal chains. These are laws that cannot be violated; only enforced. And the sword of Justice, double-edged as always, is ready to mete out punishment for those who have wronged, and to reward those who have done good deeds.
The two most important laws governed by Justice are really two sides of the same coin. First comes the law of cause and effect, stating that all events are connected and each present state is the result of all past states. This is a such strange idea to get your mind around because sometimes seemlingly meaningless actions will have great ramifications. Justice shows that every action you do will eventually have an effect, someday, and you really have no idea of knowing what that event is until it happens. Often the figure on the Justice card is pictured sitting in front of a curtain; this curtain hides the machinations of the universe that bring about these final results.
From the law of cause and order develops the law of Karma, showing that all your actions will return to you eventually. They will be modified slightly, and they are often strengthened over time, but the lesson is still the same. As you sow, so shall you reap. This is really a simple elaboration of the law of cause and effect. Under this new law, not only will everything you do have an effect, everything you do will have an effect on you. This is where it becomes critical to be mindful of your actions, because everything you take will come back to you eventually. Before Justice, you have to answer for all your actions, right and wrong. Life, if nothing else, is fair.
Indeed, Justice teaches the fairest yet cruelest lesson of all because, like in the suit of Swords, her blade has a double edge. You do not get what you expect, or even what you want - you get what you deserve. If you deserve good things then they are awarded, without ceremony or congratulation. If you deserve punishment then it is given with neither compassion nor mockery. You simply get back what you have made for yourself. And since you cannot change your actions once they have been made, if you want good things to happen you must be constantly making choices that will lead to those good things. You can be a saint or a demon - it is your choice.
When Justice appears, it should be taken as a stern reminder that the deeds of the past form the foundation for the events of the present and the future. If, in the past, you did something that you have been feeling guilty about, now may be the day when you have to answer for your deeds. If you did a deed you felt was worthy of reward, perhaps that reward will arrive. Especially when the Justice card is around, mind your actions and make sure you don't do anything you might regret later. Justice often appears to warn you that she will meet you again soon if you stay on your current path. Whether this is good or not remains yours to decide.
Despite the fact that it rarely represents the decisions of judges, this card can sometimes personify the attitude of a good judge. You may wish to take on this attitude to solve a problem in your life. The archetypal judge shown by Justice is not the blind courtroom statuette, but a figurehead of fairness and authority. Be right and reasonable in all your judgements - never take sides, never show mercy but never show excessive severity either. And before you judge others you must be prepared to judge yourself, and ensure that you are not guilty of the same errors as they. Righting any wrongs in your past must be done before you can attempt to right wrongs in your present.