It is the definition of Law. Paul tells us that the Law was good, but only brought death (through sin). Jesus frees us from sin. If Jesus does not break the law, but the law brought sin which Jesus frees us from, there must be a different meaning to Law that Jesus is using.
Jesus himself hints at it. "You heard it said..." It isn't eye for an eye, but turn the other cheek. It isn't hate your enemy, but love your enemy. He even tells us that the law is not complete when he tells us the issue about Moses and divorce.
So what does all that mean? There are multiple laws. There is the law of the Father, and the law of the creator. Ptolemy lets us know this through Flora. Some of the law given were from the Father, some from the Craftsman and others through the Elders. Jesus does not break the law of the Father, fulfills the law of the Craftsman (makes it whole; correct it), and rejects the law of the Elders.