My understanding, which is admittedly lacking, is that the law is broken up into different categories for different purposes. The overriding law is God's moral law which is summed up in the Ten Commandments but is then clearly illustrated by Jesus in the two principle laws - Love God and love your neighbor. In essence, if you do that, you can't help but be in compliance with the rest of God's moral law.
There were additional laws regarding temple worship, regarding cleanliness and health, and regarding the attempt at raising Israel to a pure model theocracy that the rest of the world could look to. On top of all of that was a series of case law that basically applied all of that to decide individual cases and establish precedents.
The important fact is that the New Covenant did not abolish God's moral law. Jesus said in fact that he came to fulfill the law, not do away with it. Paul repeatedly turns to the law as our ongoing guide to understand our sinful state. It is only the laws dealing with certain things in context of culture and period which the New Testament deemed inapplicable. But none of that changed the base moral law of God.