We read the words of the Law inLeviticus 11 that expressly prohibit the eating of certain foods, they are declared unclean. Yet Jesus tells a crowd of observant Jews to ignore this command!
Jesus called the crowd to him and said, "Listen and understand. What goes into a man's mouth does not make him 'unclean,' but what comes out of his mouth, that is what makes him 'unclean.'
How then are we to account for Jesus words about the Law in the Sermon on the Mount?
Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. I tell you the truth, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished. Anyone who breaks one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven, but whoever practices and teaches these commands will be called great in the kingdom of heaven. For I tell you that unless your righteousness surpasses that of the Pharisees and the teachers of the law, you will certainly not enter the kingdom of heaven.
Jesus is 'fulfilling the Law' yet also seemingly breaking the Law and even encouraging others to set aside what it says, at least one specific portion of it...
If you have ever been around someone who has mastered some skill, albeit a sport, painting, a musical instrument, woodworking, or cooking, you will see the same thing. I am not talking about someone who is good, or even great among their peers, but rather, a practitioner that stands as a giant above the generations before and since.
Think Albert Einstein, Claude Monet, Florence Nightingale, or Thelonious Monk, I am personally familiar with wrestlers John Smith (2x Olympic Gold Medalist) and Stephen Abas (3x NCAA Champion). These were people that in some sense 'broke the rules' of their craft, setting aside the decades, or even centuries, of wisdom from previous practitioners, and yet, in doing so they were not setting aside the craft itself, but rather somehow extending it, making it better, and more true to itself. We could easily add to the list of names...
What these individuals possessed was a mastery of craft that actually exceeds the craft itself! They were each able (in the case of science, painting, medicine, music, and wrestling) to take the craft and learn it, understand the rules, the guidelines, the practices, the craft itself, to such a degree that they were able to move beyond the rules, guidelines and practices, yet remain true to the craft itself!
This is precisely what Jesus is with respect to the Law.
He is a Master of the Law, a Master of Righteousness, a Master of Love. The course of righteousness to which the Law is a guide is the constant path of Jesus' feet, and even without the Law to guide them, those feet would stay the course...
Jesus is the 'fulfillment' of the Law.